Walk items schema instead of walking instance data (#993)

14 files changed, 839 insertions, 63 deletions

diff --git a/src/main/java/com/networknt/schema/AdditionalPropertiesValidator.java b/src/main/java/com/networknt/schema/AdditionalPropertiesValidator.java
index 62262ba..48b5f7d 100644
--- a/src/main/java/com/networknt/schema/AdditionalPropertiesValidator.java
+++ b/src/main/java/com/networknt/schema/AdditionalPropertiesValidator.java
@@ -165,7 +165,7 @@ public class AdditionalPropertiesValidator extends BaseJsonValidator {
 

     @Override

     public Set<ValidationMessage> walk(ExecutionContext executionContext, JsonNode node, JsonNode rootNode, JsonNodePath instanceLocation, boolean shouldValidateSchema) {

-        if (shouldValidateSchema) {

+        if (shouldValidateSchema && node != null) {

             return validate(executionContext, node, rootNode, instanceLocation);

         }

 

diff --git a/src/main/java/com/networknt/schema/DynamicRefValidator.java b/src/main/java/com/networknt/schema/DynamicRefValidator.java
index 6f72993..7d68d23 100644
--- a/src/main/java/com/networknt/schema/DynamicRefValidator.java
+++ b/src/main/java/com/networknt/schema/DynamicRefValidator.java
@@ -113,6 +113,22 @@ public class DynamicRefValidator extends BaseJsonValidator {
                     .arguments(schemaNode.asText()).build();

             throw new InvalidSchemaRefException(validationMessage);

         }

+        if (node == null) {

+            // Check for circular dependency

+            SchemaLocation schemaLocation = refSchema.getSchemaLocation();

+            JsonSchema check = refSchema;

+            boolean circularDependency = false;

+            while (check.getEvaluationParentSchema() != null) {

+                check = check.getEvaluationParentSchema();

+                if (check.getSchemaLocation().equals(schemaLocation)) {

+                    circularDependency = true;

+                    break;

+                }

+            }

+            if (circularDependency) {

+                return Collections.emptySet();

+            }

+        }

         return refSchema.walk(executionContext, node, rootNode, instanceLocation, shouldValidateSchema);

     }

 

diff --git a/src/main/java/com/networknt/schema/ItemsValidator.java b/src/main/java/com/networknt/schema/ItemsValidator.java
index 7aede16..7912ebd 100644
--- a/src/main/java/com/networknt/schema/ItemsValidator.java
+++ b/src/main/java/com/networknt/schema/ItemsValidator.java
@@ -203,25 +203,125 @@ public class ItemsValidator extends BaseJsonValidator {
 
     @Override
     public Set<ValidationMessage> walk(ExecutionContext executionContext, JsonNode node, JsonNode rootNode, JsonNodePath instanceLocation, boolean shouldValidateSchema) {
-        HashSet<ValidationMessage> validationMessages = new LinkedHashSet<>();
-        if (node instanceof ArrayNode) {
-            ArrayNode arrayNode = (ArrayNode) node;
-            JsonNode defaultNode = null;
-            if (this.validationContext.getConfig().getApplyDefaultsStrategy().shouldApplyArrayDefaults()
-                    && this.schema != null) {
-                defaultNode = getDefaultNode(this.schema);
+        Set<ValidationMessage> validationMessages = new LinkedHashSet<>();
+        boolean collectAnnotations = collectAnnotations();
+
+        // Add items annotation
+        if (collectAnnotations || collectAnnotations(executionContext)) {
+            if (this.schema != null) {
+                // Applies to all
+                executionContext.getAnnotations()
+                        .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                .evaluationPath(this.evaluationPath).schemaLocation(this.schemaLocation)
+                                .keyword(getKeyword()).value(true).build());
+            } else if (this.tupleSchema != null) {
+                // Tuples
+                int items = node.isArray() ? node.size() : 1;
+                int schemas = this.tupleSchema.size();
+                if (items > schemas) {
+                    // More items than schemas so the keyword only applied to the number of schemas
+                    executionContext.getAnnotations()
+                            .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                    .evaluationPath(this.evaluationPath).schemaLocation(this.schemaLocation)
+                                    .keyword(getKeyword()).value(schemas).build());
+                } else {
+                    // Applies to all
+                    executionContext.getAnnotations()
+                            .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                    .evaluationPath(this.evaluationPath).schemaLocation(this.schemaLocation)
+                                    .keyword(getKeyword()).value(true).build());
+                }
             }
-            int i = 0;
-            for (JsonNode n : arrayNode) {
-                if (n.isNull() && defaultNode != null) {
-                    arrayNode.set(i, defaultNode);
-                    n = defaultNode;
+        }
+
+        if (this.schema != null) {
+            // Walk the schema.
+            if (node instanceof ArrayNode) {
+                int count = Math.max(1, node.size());
+                ArrayNode arrayNode = (ArrayNode) node;
+                JsonNode defaultNode = null;
+                if (this.validationContext.getConfig().getApplyDefaultsStrategy().shouldApplyArrayDefaults()) {
+                    defaultNode = getDefaultNode(this.schema);
+                }
+                for (int i = 0; i < count; i++) {
+                    JsonNode n = arrayNode.get(i);
+                    if (n != null) {
+                        if (n.isNull() && defaultNode != null) {
+                            arrayNode.set(i, defaultNode);
+                            n = defaultNode;
+                        }
+                    }
+                    walkSchema(executionContext, this.schema, n, rootNode, instanceLocation.append(i), shouldValidateSchema, validationMessages, ValidatorTypeCode.ITEMS.getValue());
+                }
+            } else {
+                walkSchema(executionContext, this.schema, null, rootNode, instanceLocation.append(0), shouldValidateSchema, validationMessages, ValidatorTypeCode.ITEMS.getValue());
+            }
+        }
+        else if (this.tupleSchema != null) {
+            int prefixItems = this.tupleSchema.size();
+            for (int i = 0; i < prefixItems; i++) {
+                // walk tuple schema
+                if (node instanceof ArrayNode) {
+                    ArrayNode arrayNode = (ArrayNode) node;
+                    JsonNode defaultNode = null;
+                    JsonNode n = arrayNode.get(i);
+                    if (this.validationContext.getConfig().getApplyDefaultsStrategy().shouldApplyArrayDefaults()) {
+                        defaultNode = getDefaultNode(this.tupleSchema.get(i));
+                    }
+                    if (n != null) {
+                        if (n.isNull() && defaultNode != null) {
+                            arrayNode.set(i, defaultNode);
+                            n = defaultNode;
+                        }
+                    }
+                    walkSchema(executionContext, this.tupleSchema.get(i), n, rootNode, instanceLocation.append(i),
+                            shouldValidateSchema, validationMessages, ValidatorTypeCode.ITEMS.getValue());
+                } else {
+                    walkSchema(executionContext, this.tupleSchema.get(i), null, rootNode, instanceLocation.append(i),
+                            shouldValidateSchema, validationMessages, ValidatorTypeCode.ITEMS.getValue());
+                }
+            }
+            if (this.additionalSchema != null) {
+                boolean hasAdditionalItem = false;
+
+                int additionalItems = Math.max(1, (node != null ? node.size() : 0) - prefixItems);
+                for (int x = 0; x < additionalItems; x++) {
+                    int i = x + prefixItems;
+                    // walk additional item schema
+                    if (node instanceof ArrayNode) {
+                        ArrayNode arrayNode = (ArrayNode) node;
+                        JsonNode defaultNode = null;
+                        JsonNode n = arrayNode.get(i);
+                        if (this.validationContext.getConfig().getApplyDefaultsStrategy().shouldApplyArrayDefaults()) {
+                            defaultNode = getDefaultNode(this.additionalSchema);
+                        }
+                        if (n != null) {
+                            if (n.isNull() && defaultNode != null) {
+                                arrayNode.set(i, defaultNode);
+                                n = defaultNode;
+                            }
+                        }
+                        walkSchema(executionContext, this.additionalSchema, n, rootNode, instanceLocation.append(i),
+                                shouldValidateSchema, validationMessages, PROPERTY_ADDITIONAL_ITEMS);
+                        if (n != null) {
+                            hasAdditionalItem = true;
+                        }
+                    } else {
+                        walkSchema(executionContext, this.additionalSchema, null, rootNode, instanceLocation.append(i),
+                                shouldValidateSchema, validationMessages, PROPERTY_ADDITIONAL_ITEMS);
+                    }
+                }
+
+                if (hasAdditionalItem) {
+                    if (collectAnnotations || collectAnnotations(executionContext, "additionalItems")) {
+                        executionContext.getAnnotations()
+                                .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                        .evaluationPath(this.additionalItemsEvaluationPath)
+                                        .schemaLocation(this.additionalItemsSchemaLocation)
+                                        .keyword("additionalItems").value(true).build());
+                    }
                 }
-                doWalk(executionContext, validationMessages, i, n, rootNode, instanceLocation, shouldValidateSchema);
-                i++;
             }
-        } else {
-            doWalk(executionContext, validationMessages, 0, node, rootNode, instanceLocation, shouldValidateSchema);
         }
         return validationMessages;
     }
@@ -237,36 +337,14 @@ public class ItemsValidator extends BaseJsonValidator {
         return result;
     }
 
-    private void doWalk(ExecutionContext executionContext, HashSet<ValidationMessage> validationMessages, int i, JsonNode node,
-            JsonNode rootNode, JsonNodePath instanceLocation, boolean shouldValidateSchema) {
-        if (this.schema != null) {
-            // Walk the schema.
-            walkSchema(executionContext, this.schema, node, rootNode, instanceLocation.append(i), shouldValidateSchema, validationMessages);
-        }
-
-        if (this.tupleSchema != null) {
-            if (i < this.tupleSchema.size()) {
-                // walk tuple schema
-                walkSchema(executionContext, this.tupleSchema.get(i), node, rootNode, instanceLocation.append(i),
-                        shouldValidateSchema, validationMessages);
-            } else {
-                if (this.additionalSchema != null) {
-                    // walk additional item schema
-                    walkSchema(executionContext, this.additionalSchema, node, rootNode, instanceLocation.append(i),
-                            shouldValidateSchema, validationMessages);
-                }
-            }
-        }
-    }
-
     private void walkSchema(ExecutionContext executionContext, JsonSchema walkSchema, JsonNode node, JsonNode rootNode,
-            JsonNodePath instanceLocation, boolean shouldValidateSchema, Set<ValidationMessage> validationMessages) {
-        boolean executeWalk = this.validationContext.getConfig().getItemWalkListenerRunner().runPreWalkListeners(executionContext, ValidatorTypeCode.ITEMS.getValue(),
+            JsonNodePath instanceLocation, boolean shouldValidateSchema, Set<ValidationMessage> validationMessages, String keyword) {
+        boolean executeWalk = this.validationContext.getConfig().getItemWalkListenerRunner().runPreWalkListeners(executionContext, keyword,
                 node, rootNode, instanceLocation, walkSchema, this);
         if (executeWalk) {
             validationMessages.addAll(walkSchema.walk(executionContext, node, rootNode, instanceLocation, shouldValidateSchema));
         }
-        this.validationContext.getConfig().getItemWalkListenerRunner().runPostWalkListeners(executionContext, ValidatorTypeCode.ITEMS.getValue(), node, rootNode,
+        this.validationContext.getConfig().getItemWalkListenerRunner().runPostWalkListeners(executionContext, keyword, node, rootNode,
                 instanceLocation, walkSchema, this, validationMessages);
 
     }
diff --git a/src/main/java/com/networknt/schema/ItemsValidator202012.java b/src/main/java/com/networknt/schema/ItemsValidator202012.java
index a9cd02a..9edcb37 100644
--- a/src/main/java/com/networknt/schema/ItemsValidator202012.java
+++ b/src/main/java/com/networknt/schema/ItemsValidator202012.java
@@ -122,6 +122,7 @@ public class ItemsValidator202012 extends BaseJsonValidator {
                     && this.schema != null) {
                 defaultNode = getDefaultNode(this.schema);
             }
+            boolean evaluated = false;
             for (int i = this.prefixCount; i < node.size(); ++i) {
                 JsonNode n = node.get(i);
                 if (n.isNull() && defaultNode != null) {
@@ -131,10 +132,24 @@ public class ItemsValidator202012 extends BaseJsonValidator {
                 // Walk the schema.
                 walkSchema(executionContext, this.schema, n, rootNode, instanceLocation.append(i), shouldValidateSchema,
                         validationMessages);
+                if (n != null) {
+                    evaluated = true;
+                }
+            }
+            if (evaluated) {
+                if (collectAnnotations() || collectAnnotations(executionContext)) {
+                    // Applies to all
+                    executionContext.getAnnotations()
+                            .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                    .evaluationPath(this.evaluationPath).schemaLocation(this.schemaLocation)
+                                    .keyword(getKeyword()).value(true).build());
+                }
             }
         } else {
-            walkSchema(executionContext, this.schema, node, rootNode, instanceLocation, shouldValidateSchema,
-                    validationMessages);
+            // If the node is not an ArrayNode, eg. ObjectNode or null then the instance is null.
+            // The instance location starts at the end of the prefix count.
+            walkSchema(executionContext, this.schema, null, rootNode, instanceLocation.append(this.prefixCount),
+                    shouldValidateSchema, validationMessages);
         }
 
         return validationMessages;
@@ -150,7 +165,7 @@ public class ItemsValidator202012 extends BaseJsonValidator {
         }
         return result;
     }
-    
+
     private void walkSchema(ExecutionContext executionContext, JsonSchema walkSchema, JsonNode node, JsonNode rootNode,
             JsonNodePath instanceLocation, boolean shouldValidateSchema, Set<ValidationMessage> validationMessages) {
         //@formatter:off
diff --git a/src/main/java/com/networknt/schema/JsonValidator.java b/src/main/java/com/networknt/schema/JsonValidator.java
index fe4b71a..158a095 100644
--- a/src/main/java/com/networknt/schema/JsonValidator.java
+++ b/src/main/java/com/networknt/schema/JsonValidator.java
@@ -59,6 +59,10 @@ public interface JsonValidator extends JsonSchemaWalker {
     @Override

     default Set<ValidationMessage> walk(ExecutionContext executionContext, JsonNode node, JsonNode rootNode,

             JsonNodePath instanceLocation, boolean shouldValidateSchema) {

+        if (node == null) {

+            // Note that null is not the same as NullNode

+            return Collections.emptySet();

+        }

         return shouldValidateSchema ? validate(executionContext, node, rootNode, instanceLocation)

                 : Collections.emptySet();

     }

diff --git a/src/main/java/com/networknt/schema/PrefixItemsValidator.java b/src/main/java/com/networknt/schema/PrefixItemsValidator.java
index 94bd136..ccda858 100644
--- a/src/main/java/com/networknt/schema/PrefixItemsValidator.java
+++ b/src/main/java/com/networknt/schema/PrefixItemsValidator.java
@@ -47,8 +47,11 @@ public class PrefixItemsValidator extends BaseJsonValidator {
         this.tupleSchema = new ArrayList<>();
 
         if (schemaNode instanceof ArrayNode && 0 < schemaNode.size()) {
+            int i = 0;
             for (JsonNode s : schemaNode) {
-                this.tupleSchema.add(validationContext.newSchema(schemaLocation, evaluationPath, s, parentSchema));
+                this.tupleSchema.add(validationContext.newSchema(schemaLocation.append(i), evaluationPath.append(i), s,
+                        parentSchema));
+                i++;
             }
         } else {
             throw new IllegalArgumentException("The value of 'prefixItems' MUST be a non-empty array of valid JSON Schemas.");
@@ -101,22 +104,49 @@ public class PrefixItemsValidator extends BaseJsonValidator {
     @Override
     public Set<ValidationMessage> walk(ExecutionContext executionContext, JsonNode node, JsonNode rootNode, JsonNodePath instanceLocation, boolean shouldValidateSchema) {
         Set<ValidationMessage> validationMessages = new LinkedHashSet<>();
-
-        if (this.validationContext.getConfig().getApplyDefaultsStrategy().shouldApplyArrayDefaults()
-                && node.isArray()) {
+        if (node instanceof ArrayNode) {
             ArrayNode array = (ArrayNode) node;
-            int count = Math.min(node.size(), this.tupleSchema.size());
+            int count = this.tupleSchema.size();
             for (int i = 0; i < count; ++i) {
                 JsonNode n = node.get(i);
-                JsonNode defaultNode = getDefaultNode(this.tupleSchema.get(i));
-                if (n.isNull() && defaultNode != null) {
-                    array.set(i, defaultNode);
-                    n = defaultNode;
+                if (this.validationContext.getConfig().getApplyDefaultsStrategy().shouldApplyArrayDefaults()) {
+                    JsonNode defaultNode = getDefaultNode(this.tupleSchema.get(i));
+                    if (n != null) {
+                        // Defaults only set if array index is explicitly null
+                        if (n.isNull() && defaultNode != null) {
+                            array.set(i, defaultNode);
+                            n = defaultNode;
+                        }
+                    }
                 }
                 doWalk(executionContext, validationMessages, i, n, rootNode, instanceLocation, shouldValidateSchema);
             }
-        }
 
+            // Add annotation
+            if (collectAnnotations() || collectAnnotations(executionContext)) {
+                // Tuples
+                int items = node.isArray() ? node.size() : 1;
+                int schemas = this.tupleSchema.size();
+                if (items > schemas) {
+                    // More items than schemas so the keyword only applied to the number of schemas
+                    executionContext.getAnnotations()
+                            .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                    .evaluationPath(this.evaluationPath).schemaLocation(this.schemaLocation)
+                                    .keyword(getKeyword()).value(schemas).build());
+                } else {
+                    // Applies to all
+                    executionContext.getAnnotations()
+                            .put(JsonNodeAnnotation.builder().instanceLocation(instanceLocation)
+                                    .evaluationPath(this.evaluationPath).schemaLocation(this.schemaLocation)
+                                    .keyword(getKeyword()).value(true).build());
+                }
+            }
+        } else {
+            int count = this.tupleSchema.size();
+            for (int i = 0; i < count; ++i) {
+                doWalk(executionContext, validationMessages, i, null, rootNode, instanceLocation, shouldValidateSchema);
+            }
+        }
         return validationMessages;
     }
 
diff --git a/src/main/java/com/networknt/schema/PropertiesValidator.java b/src/main/java/com/networknt/schema/PropertiesValidator.java
index a47e61c..f378905 100644
--- a/src/main/java/com/networknt/schema/PropertiesValidator.java
+++ b/src/main/java/com/networknt/schema/PropertiesValidator.java
@@ -18,6 +18,7 @@ package com.networknt.schema;
 

 import com.fasterxml.jackson.databind.JsonNode;

 import com.fasterxml.jackson.databind.node.JsonNodeType;

+import com.fasterxml.jackson.databind.node.MissingNode;

 import com.fasterxml.jackson.databind.node.ObjectNode;

 import com.networknt.schema.annotation.JsonNodeAnnotation;

 import com.networknt.schema.utils.JsonSchemaRefs;

@@ -99,7 +100,7 @@ public class PropertiesValidator extends BaseJsonValidator {
                     if (errors == null) {

                         errors = new SetView<>();

                     }

-                    walkSchema(executionContext, entry, node, rootNode, instanceLocation, state.isValidationEnabled(), errors, this.validationContext.getConfig().getPropertyWalkListenerRunner(), false);

+                    walkSchema(executionContext, entry, node, rootNode, instanceLocation, state.isValidationEnabled(), errors, this.validationContext.getConfig().getPropertyWalkListenerRunner());

                 }

 

                 // reset the complex flag to the original value before the recursive call

@@ -118,7 +119,7 @@ public class PropertiesValidator extends BaseJsonValidator {
                     if (errors == null) {

                         errors = new SetView<>();

                     }

-                    walkSchema(executionContext, entry, node, rootNode, instanceLocation, state.isValidationEnabled(), errors, this.validationContext.getConfig().getPropertyWalkListenerRunner(), true);

+                    walkSchema(executionContext, entry, node, rootNode, instanceLocation, state.isValidationEnabled(), errors, this.validationContext.getConfig().getPropertyWalkListenerRunner());

                 }

 

                 // check whether the node which has not matched was mandatory or not

@@ -165,11 +166,12 @@ public class PropertiesValidator extends BaseJsonValidator {
             applyPropertyDefaults((ObjectNode) node);

         }

         if (shouldValidateSchema) {

-            validationMessages.union(validate(executionContext, node, rootNode, instanceLocation));

+            validationMessages.union(validate(executionContext, node == null ? MissingNode.getInstance() : node, rootNode,

+                    instanceLocation));

         } else {

             WalkListenerRunner propertyWalkListenerRunner = this.validationContext.getConfig().getPropertyWalkListenerRunner();

             for (Map.Entry<String, JsonSchema> entry : this.schemas.entrySet()) {

-                walkSchema(executionContext, entry, node, rootNode, instanceLocation, shouldValidateSchema, validationMessages, propertyWalkListenerRunner, false);

+                walkSchema(executionContext, entry, node, rootNode, instanceLocation, shouldValidateSchema, validationMessages, propertyWalkListenerRunner);

             }

         }

         return validationMessages;

@@ -215,7 +217,7 @@ public class PropertiesValidator extends BaseJsonValidator {
 

     private void walkSchema(ExecutionContext executionContext, Map.Entry<String, JsonSchema> entry, JsonNode node,

             JsonNode rootNode, JsonNodePath instanceLocation, boolean shouldValidateSchema,

-            SetView<ValidationMessage> validationMessages, WalkListenerRunner propertyWalkListenerRunner, boolean skipWalk) {

+            SetView<ValidationMessage> validationMessages, WalkListenerRunner propertyWalkListenerRunner) {

         JsonSchema propertySchema = entry.getValue();

         JsonNode propertyNode = (node == null ? null : node.get(entry.getKey()));

         JsonNodePath path = instanceLocation.append(entry.getKey());

@@ -226,7 +228,7 @@ public class PropertiesValidator extends BaseJsonValidator {
             // Attempt to get the property node again in case the propertyNode was updated

             propertyNode = node.get(entry.getKey());

         }

-        if (executeWalk && !(skipWalk && propertyNode == null)) {

+        if (executeWalk) {

             validationMessages.union(

                     propertySchema.walk(executionContext, propertyNode, rootNode, path, shouldValidateSchema));

         }

diff --git a/src/main/java/com/networknt/schema/RecursiveRefValidator.java b/src/main/java/com/networknt/schema/RecursiveRefValidator.java
index e73bb7d..8cd0de7 100644
--- a/src/main/java/com/networknt/schema/RecursiveRefValidator.java
+++ b/src/main/java/com/networknt/schema/RecursiveRefValidator.java
@@ -110,6 +110,22 @@ public class RecursiveRefValidator extends BaseJsonValidator {
                     .arguments(schemaNode.asText()).build();

             throw new InvalidSchemaRefException(validationMessage);

         }

+        if (node == null) {

+            // Check for circular dependency

+            SchemaLocation schemaLocation = refSchema.getSchemaLocation();

+            JsonSchema check = refSchema;

+            boolean circularDependency = false;

+            while (check.getEvaluationParentSchema() != null) {

+                check = check.getEvaluationParentSchema();

+                if (check.getSchemaLocation().equals(schemaLocation)) {

+                    circularDependency = true;

+                    break;

+                }

+            }

+            if (circularDependency) {

+                return Collections.emptySet();

+            }

+        }

         return refSchema.walk(executionContext, node, rootNode, instanceLocation, shouldValidateSchema);

     }

 

diff --git a/src/main/java/com/networknt/schema/RefValidator.java b/src/main/java/com/networknt/schema/RefValidator.java
index 1a32e6e..e6b803e 100644
--- a/src/main/java/com/networknt/schema/RefValidator.java
+++ b/src/main/java/com/networknt/schema/RefValidator.java
@@ -195,6 +195,22 @@ public class RefValidator extends BaseJsonValidator {
                     .arguments(schemaNode.asText()).build();

             throw new InvalidSchemaRefException(validationMessage);

         }

+        if (node == null) {

+            // Check for circular dependency

+            SchemaLocation schemaLocation = refSchema.getSchemaLocation();

+            JsonSchema check = refSchema;

+            boolean circularDependency = false;

+            while (check.getEvaluationParentSchema() != null) {

+                check = check.getEvaluationParentSchema();

+                if (check.getSchemaLocation().equals(schemaLocation)) {

+                    circularDependency = true;

+                    break;

+                }

+            }

+            if (circularDependency) {

+                return Collections.emptySet();

+            }

+        }

         return refSchema.walk(executionContext, node, rootNode, instanceLocation, shouldValidateSchema);

     }

 

diff --git a/src/test/java/com/networknt/schema/ItemsValidator202012Test.java b/src/test/java/com/networknt/schema/ItemsValidator202012Test.java
index 401e182..f7330f3 100644
--- a/src/test/java/com/networknt/schema/ItemsValidator202012Test.java
+++ b/src/test/java/com/networknt/schema/ItemsValidator202012Test.java
@@ -18,12 +18,18 @@ package com.networknt.schema;
 import static org.junit.jupiter.api.Assertions.assertEquals;

 import static org.junit.jupiter.api.Assertions.assertFalse;

 import static org.junit.jupiter.api.Assertions.assertNull;

+import static org.junit.jupiter.api.Assertions.assertTrue;

 

+import java.util.ArrayList;

+import java.util.List;

 import java.util.Set;

 

 import org.junit.jupiter.api.Test;

 

 import com.networknt.schema.SpecVersion.VersionFlag;

+import com.networknt.schema.walk.JsonSchemaWalkListener;

+import com.networknt.schema.walk.WalkEvent;

+import com.networknt.schema.walk.WalkFlow;

 

 /**

  * ItemsValidatorTest.

@@ -55,4 +61,86 @@ public class ItemsValidator202012Test {
         assertEquals("/1: string found, integer expected", message.getMessage());

         assertNull(message.getProperty());

     }

+

+    @Test

+    void walkNull() {

+        String schemaData = "{\r\n"

+                + "  \"items\": {\r\n"

+                + "    \"type\": \"string\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V202012);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        ValidationResult result = schema.walk(null, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+        

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(1, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+    }

+

+    @Test

+    void walkNullPrefixItems() {

+        String schemaData = "{\r\n"

+                + "  \"prefixItems\": [\r\n"

+                + "    {\r\n"

+                + "      \"type\": \"integer\"\r\n"

+                + "    }\r\n"

+                + "  ],\r\n"

+                + "  \"items\": {\r\n"

+                + "    \"type\": \"string\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V202012);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        ValidationResult result = schema.walk(null, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+        

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(2, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+        assertEquals("prefixItems", items.get(0).getKeyword());

+        assertEquals("/1", items.get(1).getInstanceLocation().toString());

+        assertEquals("items", items.get(1).getKeyword());

+    }

 }

diff --git a/src/test/java/com/networknt/schema/ItemsValidatorTest.java b/src/test/java/com/networknt/schema/ItemsValidatorTest.java
index 8823028..901dbc0 100644
--- a/src/test/java/com/networknt/schema/ItemsValidatorTest.java
+++ b/src/test/java/com/networknt/schema/ItemsValidatorTest.java
@@ -18,12 +18,22 @@ package com.networknt.schema;
 import static org.junit.jupiter.api.Assertions.assertEquals;

 import static org.junit.jupiter.api.Assertions.assertFalse;

 import static org.junit.jupiter.api.Assertions.assertNull;

+import static org.junit.jupiter.api.Assertions.assertTrue;

 

+import java.util.ArrayList;

+import java.util.List;

 import java.util.Set;

 

 import org.junit.jupiter.api.Test;

 

+import com.fasterxml.jackson.core.JsonProcessingException;

+import com.fasterxml.jackson.databind.JsonMappingException;

+import com.fasterxml.jackson.databind.JsonNode;

 import com.networknt.schema.SpecVersion.VersionFlag;

+import com.networknt.schema.serialization.JsonMapperFactory;

+import com.networknt.schema.walk.JsonSchemaWalkListener;

+import com.networknt.schema.walk.WalkEvent;

+import com.networknt.schema.walk.WalkFlow;

 

 /**

  * ItemsValidatorTest.

@@ -111,4 +121,248 @@ public class ItemsValidatorTest {
         assertEquals(": index '1' is not defined in the schema and the schema does not allow additional items", message.getMessage());

         assertNull(message.getProperty());

     }

+

+    @Test

+    void walk() {

+        String schemaData = "{\r\n"

+                + "  \"items\": {\r\n"

+                + "    \"type\": \"string\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V201909);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        ValidationResult result = schema.walk("[\"the\",\"quick\",\"brown\"]", InputFormat.JSON, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+        

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(3, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+        assertEquals("/1", items.get(1).getInstanceLocation().toString());

+        assertEquals("/2", items.get(2).getInstanceLocation().toString());

+    }

+

+    @Test

+    void walkNull() {

+        String schemaData = "{\r\n"

+                + "  \"items\": {\r\n"

+                + "    \"type\": \"string\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V201909);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        ValidationResult result = schema.walk(null, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+        

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(1, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+    }

+

+    @Test

+    void walkNullTupleItemsAdditional() {

+        String schemaData = "{\r\n"

+                + "  \"items\": [\r\n"

+                + "    {\r\n"

+                + "      \"type\": \"string\"\r\n"

+                + "    }\r\n,"

+                + "    {\r\n"

+                + "      \"type\": \"integer\"\r\n"

+                + "    }\r\n"

+                + "  ],\r\n"

+                + "  \"additionalItems\": {\r\n"

+                + "    \"type\": \"string\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V201909);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        ValidationResult result = schema.walk(null, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(3, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+        assertEquals("items", items.get(0).getKeyword());

+        assertNull(items.get(0).getInstanceNode());

+        assertEquals("/1", items.get(1).getInstanceLocation().toString());

+        assertEquals("items", items.get(1).getKeyword());

+        assertNull(items.get(1).getInstanceNode());

+        assertEquals("/2", items.get(2).getInstanceLocation().toString());

+        assertEquals("additionalItems", items.get(2).getKeyword());

+        assertNull(items.get(2).getInstanceNode());

+    }

+

+    @Test

+    void walkTupleItemsAdditional() throws JsonMappingException, JsonProcessingException {

+        String schemaData = "{\r\n"

+                + "  \"items\": [\r\n"

+                + "    {\r\n"

+                + "      \"type\": \"string\"\r\n"

+                + "    }\r\n,"

+                + "    {\r\n"

+                + "      \"type\": \"integer\"\r\n"

+                + "    }\r\n"

+                + "  ],\r\n"

+                + "  \"additionalItems\": {\r\n"

+                + "    \"type\": \"string\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V201909);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        JsonNode input = JsonMapperFactory.getInstance().readTree("[\"hello\"]");

+        ValidationResult result = schema.walk(input, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(3, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+        assertEquals("items", items.get(0).getKeyword());

+        assertEquals("hello", items.get(0).getInstanceNode().textValue());

+        assertEquals("/1", items.get(1).getInstanceLocation().toString());

+        assertEquals("items", items.get(1).getKeyword());

+        assertNull(items.get(1).getInstanceNode());

+        assertEquals("/2", items.get(2).getInstanceLocation().toString());

+        assertEquals("additionalItems", items.get(2).getKeyword());

+        assertNull(items.get(2).getInstanceNode());

+    }

+

+    @Test

+    void walkTupleItemsAdditionalDefaults() throws JsonMappingException, JsonProcessingException {

+        String schemaData = "{\r\n"

+                + "  \"items\": [\r\n"

+                + "    {\r\n"

+                + "      \"type\": \"string\",\r\n"

+                + "      \"default\": \"1\"\r\n"

+                + "    },\r\n"

+                + "    {\r\n"

+                + "      \"type\": \"integer\",\r\n"

+                + "      \"default\": 2\r\n"

+                + "    }\r\n"

+                + "  ],\r\n"

+                + "  \"additionalItems\": {\r\n"

+                + "    \"type\": \"string\",\r\n"

+                + "    \"default\": \"additional\"\r\n"

+                + "  }\r\n"

+                + "}";

+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V201909);

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.setApplyDefaultsStrategy(new ApplyDefaultsStrategy(true, true, true));

+        config.setPathType(PathType.JSON_POINTER);

+        config.addItemWalkListener(new JsonSchemaWalkListener() {

+            

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+            

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        });

+        JsonSchema schema = factory.getSchema(schemaData, config);

+        JsonNode input = JsonMapperFactory.getInstance().readTree("[null, null, null, null]");

+        ValidationResult result = schema.walk(input, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(4, items.size());

+        assertEquals("/0", items.get(0).getInstanceLocation().toString());

+        assertEquals("items", items.get(0).getKeyword());

+        assertEquals("1", items.get(0).getInstanceNode().textValue());

+        assertEquals("/1", items.get(1).getInstanceLocation().toString());

+        assertEquals("items", items.get(1).getKeyword());

+        assertEquals(2, items.get(1).getInstanceNode().intValue());

+        assertEquals("/2", items.get(2).getInstanceLocation().toString());

+        assertEquals("additionalItems", items.get(2).getKeyword());

+        assertEquals("additional", items.get(2).getInstanceNode().asText());

+        assertEquals("/3", items.get(3).getInstanceLocation().toString());

+        assertEquals("additionalItems", items.get(3).getKeyword());

+        assertEquals("additional", items.get(3).getInstanceNode().asText());

+    }

 }

diff --git a/src/test/java/com/networknt/schema/PrefixItemsValidatorTest.java b/src/test/java/com/networknt/schema/PrefixItemsValidatorTest.java
index b57d822..a06eda4 100644
--- a/src/test/java/com/networknt/schema/PrefixItemsValidatorTest.java
+++ b/src/test/java/com/networknt/schema/PrefixItemsValidatorTest.java
@@ -4,8 +4,17 @@ import org.junit.jupiter.api.DynamicContainer;
 import org.junit.jupiter.api.DynamicNode;
 import org.junit.jupiter.api.Test;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.JsonMappingException;
+import com.fasterxml.jackson.databind.JsonNode;
 import com.networknt.schema.SpecVersion.VersionFlag;
+import com.networknt.schema.serialization.JsonMapperFactory;
+import com.networknt.schema.walk.JsonSchemaWalkListener;
+import com.networknt.schema.walk.WalkEvent;
+import com.networknt.schema.walk.WalkFlow;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Set;
 import java.util.stream.Stream;
 
@@ -54,8 +63,8 @@ public class PrefixItemsValidatorTest extends AbstractJsonSchemaTestSuite {
         Set<ValidationMessage> messages = schema.validate(inputData, InputFormat.JSON);
         assertFalse(messages.isEmpty());
         ValidationMessage message = messages.iterator().next();
-        assertEquals("/prefixItems/type", message.getEvaluationPath().toString());
-        assertEquals("https://www.example.org/schema#/prefixItems/type", message.getSchemaLocation().toString());
+        assertEquals("/prefixItems/0/type", message.getEvaluationPath().toString());
+        assertEquals("https://www.example.org/schema#/prefixItems/0/type", message.getSchemaLocation().toString());
         assertEquals("/0", message.getInstanceLocation().toString());
         assertEquals("\"string\"", message.getSchemaNode().toString());
         assertEquals("1", message.getInstanceNode().toString());
@@ -109,4 +118,115 @@ public class PrefixItemsValidatorTest extends AbstractJsonSchemaTestSuite {
         assertEquals(": index '2' is not defined in the schema and the schema does not allow additional items", message.getMessage());
         assertNull(message.getProperty());
     }
+
+    @Test
+    void walkNull() {
+        String schemaData = "{\n"
+                + "  \"prefixItems\": [\n"
+                + "    {\n"
+                + "      \"type\": \"integer\"\n"
+                + "    },\n"
+                + "    {\n"
+                + "      \"type\": \"string\"\n"
+                + "    },\n"
+                + "    {\n"
+                + "      \"type\": \"integer\"\n"
+                + "    }\n"
+                + "  ]\n"
+                + "}";
+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V202012);
+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();
+        config.setPathType(PathType.JSON_POINTER);
+        config.addItemWalkListener(new JsonSchemaWalkListener() {
+            
+            @Override
+            public WalkFlow onWalkStart(WalkEvent walkEvent) {
+                return WalkFlow.CONTINUE;
+            }
+            
+            @Override
+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {
+                @SuppressWarnings("unchecked")
+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()
+                        .getCollectorContext()
+                        .getCollectorMap()
+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());
+                items.add(walkEvent);
+            }
+        });
+        JsonSchema schema = factory.getSchema(schemaData, config);
+        ValidationResult result = schema.walk(null, true);
+        assertTrue(result.getValidationMessages().isEmpty());
+        
+        @SuppressWarnings("unchecked")
+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");
+        assertEquals(3, items.size());
+        assertEquals("/0", items.get(0).getInstanceLocation().toString());
+        assertEquals("prefixItems", items.get(0).getKeyword());
+        assertEquals("#/prefixItems/0", items.get(0).getSchema().getSchemaLocation().toString());
+        assertEquals("/1", items.get(1).getInstanceLocation().toString());
+        assertEquals("prefixItems", items.get(1).getKeyword());
+        assertEquals("#/prefixItems/1", items.get(1).getSchema().getSchemaLocation().toString());
+        assertEquals("/2", items.get(2).getInstanceLocation().toString());
+        assertEquals("prefixItems", items.get(2).getKeyword());
+        assertEquals("#/prefixItems/2", items.get(2).getSchema().getSchemaLocation().toString());
+    }
+
+    @Test
+    void walkDefaults() throws JsonMappingException, JsonProcessingException {
+        String schemaData = "{\n"
+                + "  \"prefixItems\": [\n"
+                + "    {\n"
+                + "      \"type\": \"integer\",\n"
+                + "      \"default\": 1\n"
+                + "    },\n"
+                + "    {\n"
+                + "      \"type\": \"string\",\n"
+                + "      \"default\": \"2\"\n"
+                + "    },\n"
+                + "    {\n"
+                + "      \"type\": \"integer\",\n"
+                + "      \"default\": 3\n"
+                + "    }\n"
+                + "  ]\n"
+                + "}";
+        JsonSchemaFactory factory = JsonSchemaFactory.getInstance(VersionFlag.V202012);
+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();
+        config.setPathType(PathType.JSON_POINTER);
+        config.setApplyDefaultsStrategy(new ApplyDefaultsStrategy(true, true, true));
+        config.addItemWalkListener(new JsonSchemaWalkListener() {
+            
+            @Override
+            public WalkFlow onWalkStart(WalkEvent walkEvent) {
+                return WalkFlow.CONTINUE;
+            }
+            
+            @Override
+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {
+                @SuppressWarnings("unchecked")
+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()
+                        .getCollectorContext()
+                        .getCollectorMap()
+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());
+                items.add(walkEvent);
+            }
+        });
+        JsonSchema schema = factory.getSchema(schemaData, config);
+        JsonNode input = JsonMapperFactory.getInstance().readTree("[null, null]");
+        ValidationResult result = schema.walk(input, true);
+        assertTrue(result.getValidationMessages().isEmpty());
+        
+        @SuppressWarnings("unchecked")
+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");
+        assertEquals(3, items.size());
+        assertEquals("/0", items.get(0).getInstanceLocation().toString());
+        assertEquals("prefixItems", items.get(0).getKeyword());
+        assertEquals("#/prefixItems/0", items.get(0).getSchema().getSchemaLocation().toString());
+        assertEquals("/1", items.get(1).getInstanceLocation().toString());
+        assertEquals("prefixItems", items.get(1).getKeyword());
+        assertEquals("#/prefixItems/1", items.get(1).getSchema().getSchemaLocation().toString());
+        assertEquals("/2", items.get(2).getInstanceLocation().toString());
+        assertEquals("prefixItems", items.get(2).getKeyword());
+        assertEquals("#/prefixItems/2", items.get(2).getSchema().getSchemaLocation().toString());
+    }
 }
diff --git a/src/test/java/com/networknt/schema/TypeValidatorTest.java b/src/test/java/com/networknt/schema/TypeValidatorTest.java
index 8560b56..487b814 100644
--- a/src/test/java/com/networknt/schema/TypeValidatorTest.java
+++ b/src/test/java/com/networknt/schema/TypeValidatorTest.java
@@ -16,6 +16,7 @@
 package com.networknt.schema;

 

 import static org.junit.jupiter.api.Assertions.assertEquals;

+import static org.junit.jupiter.api.Assertions.assertTrue;

 

 import java.util.Set;

 

@@ -139,4 +140,14 @@ public class TypeValidatorTest {
         messages = schema.validate("2.000001", InputFormat.JSON);

         assertEquals(1, messages.size());

     }

+

+    @Test

+    void walkNull() {

+        String schemaData = "{\r\n"

+                + "  \"type\": \"integer\"\r\n"

+                + "}";

+        JsonSchema schema = JsonSchemaFactory.getInstance(VersionFlag.V4).getSchema(schemaData);

+        ValidationResult result = schema.walk(null, true);

+        assertTrue(result.getValidationMessages().isEmpty());

+    }

 }

diff --git a/src/test/java/com/networknt/schema/walk/JsonSchemaWalkListenerTest.java b/src/test/java/com/networknt/schema/walk/JsonSchemaWalkListenerTest.java
index d4b6701..af19ac0 100644
--- a/src/test/java/com/networknt/schema/walk/JsonSchemaWalkListenerTest.java
+++ b/src/test/java/com/networknt/schema/walk/JsonSchemaWalkListenerTest.java
@@ -38,6 +38,7 @@ import com.networknt.schema.ApplyDefaultsStrategy;
 import com.networknt.schema.InputFormat;

 import com.networknt.schema.ItemsValidator;

 import com.networknt.schema.ItemsValidator202012;

+import com.networknt.schema.JsonNodePath;

 import com.networknt.schema.JsonSchema;

 import com.networknt.schema.JsonSchemaFactory;

 import com.networknt.schema.JsonSchemaRef;

@@ -811,4 +812,129 @@ class JsonSchemaWalkListenerTest {
         assertEquals("{\"name\":\"John Doe\",\"email\":\"john.doe@gmail.com\"}", inputNode.toString());

         assertTrue(result.getValidationMessages().isEmpty());

     }

+

+    /**

+     * Issue 989

+     */

+    @Test

+    void itemListenerDraft201909() {

+        String schemaData = "        {\r\n"

+                + "          \"type\": \"object\",\r\n"

+                + "          \"properties\": {\r\n"

+                + "            \"name\": {\r\n"

+                + "              \"type\": \"string\"\r\n"

+                + "            },\r\n"

+                + "            \"children\": {\r\n"

+                + "              \"type\": \"array\",\r\n"

+                + "              \"items\": {\r\n"

+                + "                \"type\": \"object\",\r\n"

+                + "                \"properties\": {\r\n"

+                + "                  \"name\": {\r\n"

+                + "                    \"type\": \"string\"\r\n"

+                + "                  }\r\n"

+                + "                }\r\n"

+                + "              }\r\n"

+                + "            }\r\n"

+                + "          }\r\n"

+                + "        }";

+        JsonSchemaWalkListener listener = new JsonSchemaWalkListener() {

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        }; 

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.addItemWalkListener(listener);

+        config.addPropertyWalkListener(listener);

+        JsonSchema schema = JsonSchemaFactory.getInstance(VersionFlag.V201909).getSchema(schemaData, config);

+        ValidationResult result = schema.walk(null, true);

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(4, items.size());

+        assertEquals("$.name", items.get(0).getInstanceLocation().toString());

+        assertEquals("properties", items.get(0).getKeyword());

+        assertEquals("#/properties/name", items.get(0).getSchema().getSchemaLocation().toString());

+        assertEquals("$.children[0].name", items.get(1).getInstanceLocation().toString());

+        assertEquals("properties", items.get(1).getKeyword());

+        assertEquals("#/properties/children/items/properties/name", items.get(1).getSchema().getSchemaLocation().toString());

+        assertEquals("$.children[0]", items.get(2).getInstanceLocation().toString());

+        assertEquals("items", items.get(2).getKeyword());

+        assertEquals("#/properties/children/items", items.get(2).getSchema().getSchemaLocation().toString());

+        assertEquals("$.children", items.get(3).getInstanceLocation().toString());

+        assertEquals("properties", items.get(3).getKeyword());

+        assertEquals("#/properties/children", items.get(3).getSchema().getSchemaLocation().toString());

+    }

+

+    /**

+     * Issue 989

+     */

+    @Test

+    void itemListenerDraft202012() {

+        String schemaData = "        {\r\n"

+                + "          \"type\": \"object\",\r\n"

+                + "          \"properties\": {\r\n"

+                + "            \"name\": {\r\n"

+                + "              \"type\": \"string\"\r\n"

+                + "            },\r\n"

+                + "            \"children\": {\r\n"

+                + "              \"type\": \"array\",\r\n"

+                + "              \"items\": {\r\n"

+                + "                \"type\": \"object\",\r\n"

+                + "                \"properties\": {\r\n"

+                + "                  \"name\": {\r\n"

+                + "                    \"type\": \"string\"\r\n"

+                + "                  }\r\n"

+                + "                }\r\n"

+                + "              }\r\n"

+                + "            }\r\n"

+                + "          }\r\n"

+                + "        }";

+        JsonSchemaWalkListener listener = new JsonSchemaWalkListener() {

+            @Override

+            public WalkFlow onWalkStart(WalkEvent walkEvent) {

+                return WalkFlow.CONTINUE;

+            }

+

+            @Override

+            public void onWalkEnd(WalkEvent walkEvent, Set<ValidationMessage> validationMessages) {

+                @SuppressWarnings("unchecked")

+                List<WalkEvent> items = (List<WalkEvent>) walkEvent.getExecutionContext()

+                        .getCollectorContext()

+                        .getCollectorMap()

+                        .computeIfAbsent("items", key -> new ArrayList<JsonNodePath>());

+                items.add(walkEvent);

+            }

+        }; 

+        SchemaValidatorsConfig config = new SchemaValidatorsConfig();

+        config.addItemWalkListener(listener);

+        config.addPropertyWalkListener(listener);

+        JsonSchema schema = JsonSchemaFactory.getInstance(VersionFlag.V202012).getSchema(schemaData, config);

+        ValidationResult result = schema.walk(null, true);

+        @SuppressWarnings("unchecked")

+        List<WalkEvent> items = (List<WalkEvent>) result.getExecutionContext().getCollectorContext().get("items");

+        assertEquals(4, items.size());

+        assertEquals("$.name", items.get(0).getInstanceLocation().toString());

+        assertEquals("properties", items.get(0).getKeyword());

+        assertEquals("#/properties/name", items.get(0).getSchema().getSchemaLocation().toString());

+        assertEquals("$.children[0].name", items.get(1).getInstanceLocation().toString());

+        assertEquals("properties", items.get(1).getKeyword());

+        assertEquals("#/properties/children/items/properties/name", items.get(1).getSchema().getSchemaLocation().toString());

+        assertEquals("$.children[0]", items.get(2).getInstanceLocation().toString());

+        assertEquals("items", items.get(2).getKeyword());

+        assertEquals("#/properties/children/items", items.get(2).getSchema().getSchemaLocation().toString());

+        assertEquals("$.children", items.get(3).getInstanceLocation().toString());

+        assertEquals("properties", items.get(3).getKeyword());

+        assertEquals("#/properties/children", items.get(3).getSchema().getSchemaLocation().toString());

+    }

+

 }