Modernize AutoFactory source.

* Replace `com.google.common.base.Optional` by `java.util.Optional`.
* Use streams and lambdas where appropriate.
* Use diamond operator where appropriate.
* Remove type arguments made unnecessary by Java 8's improved type inference.
* Apply some automated fixes.

RELNOTES=n/a
PiperOrigin-RevId: 339124210

11 files changed, 98 insertions, 125 deletions

diff --git a/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryDeclaration.java b/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryDeclaration.java
index e2da6eae..ec3642a9 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryDeclaration.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryDeclaration.java
@@ -27,7 +27,6 @@ import static javax.tools.Diagnostic.Kind.ERROR;
 
 import com.google.auto.factory.AutoFactory;
 import com.google.auto.value.AutoValue;
-import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
@@ -36,6 +35,7 @@ import com.google.common.collect.ImmutableSet;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import javax.annotation.processing.Messager;
 import javax.lang.model.SourceVersion;
 import javax.lang.model.element.AnnotationMirror;
@@ -110,23 +110,22 @@ abstract class AutoFactoryDeclaration {
         messager.printMessage(ERROR,
             String.format("\"%s\" is not a valid Java identifier", className),
             element, mirror, classNameValue);
-        return Optional.absent();
+        return Optional.empty();
       }
 
       AnnotationValue extendingValue = checkNotNull(values.get("extending"));
       TypeElement extendingType = AnnotationValues.asType(extendingValue);
       if (extendingType == null) {
-        messager.printMessage(ERROR, "Unable to find the type: "
-            + extendingValue.getValue().toString(),
+        messager.printMessage(ERROR, "Unable to find the type: " + extendingValue.getValue(),
                 element, mirror, extendingValue);
-        return Optional.absent();
+        return Optional.empty();
       } else if (!isValidSupertypeForClass(extendingType)) {
         messager.printMessage(ERROR,
             String.format("%s is not a valid supertype for a factory. "
                 + "Supertypes must be non-final classes.",
                     extendingType.getQualifiedName()),
             element, mirror, extendingValue);
-        return Optional.absent();
+        return Optional.empty();
       }
       ImmutableList<ExecutableElement> noParameterConstructors =
           FluentIterable.from(ElementFilter.constructorsIn(extendingType.getEnclosedElements()))
@@ -136,13 +135,13 @@ abstract class AutoFactoryDeclaration {
                 }
               })
               .toList();
-      if (noParameterConstructors.size() == 0) {
+      if (noParameterConstructors.isEmpty()) {
         messager.printMessage(ERROR,
             String.format("%s is not a valid supertype for a factory. "
                 + "Factory supertypes must have a no-arg constructor.",
                     extendingType.getQualifiedName()),
             element, mirror, extendingValue);
-        return Optional.absent();
+        return Optional.empty();
       } else if (noParameterConstructors.size() > 1) {
         throw new IllegalStateException("Multiple constructors with no parameters??");
       }
@@ -161,7 +160,7 @@ abstract class AutoFactoryDeclaration {
           new AutoValue_AutoFactoryDeclaration(
               getAnnotatedType(element),
               element,
-              className.isEmpty() ? Optional.<String>absent() : Optional.of(className),
+              className.isEmpty() ? Optional.empty() : Optional.of(className),
               extendingType,
               implementingTypes,
               allowSubclasses,
diff --git a/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java b/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java
index 5cc1d94d..b07786a5 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/AutoFactoryProcessor.java
@@ -19,7 +19,6 @@ import com.google.auto.common.MoreTypes;
 import com.google.auto.factory.AutoFactory;
 import com.google.auto.factory.Provided;
 import com.google.auto.service.AutoService;
-import com.google.common.base.Optional;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
@@ -31,6 +30,7 @@ import java.io.IOException;
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
 import javax.annotation.processing.AbstractProcessor;
 import javax.annotation.processing.Messager;
diff --git a/factory/src/main/java/com/google/auto/factory/processor/Elements2.java b/factory/src/main/java/com/google/auto/factory/processor/Elements2.java
index 30230f7f..fa00454e 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/Elements2.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/Elements2.java
@@ -22,10 +22,10 @@ import static javax.lang.model.element.ElementKind.PACKAGE;
 import static javax.lang.model.element.Modifier.FINAL;
 import static javax.lang.model.element.Modifier.STATIC;
 
+import com.google.auto.common.MoreTypes;
 import com.google.common.collect.ImmutableSet;
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
-import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.ExecutableType;
 import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
@@ -72,11 +72,11 @@ final class Elements2 {
       throw new IllegalStateException(
           "Expected subTypeElement.asType() to return a class/interface type.");
     }
-    TypeMirror subExecutableTypeMirror = types.asMemberOf(
-        (DeclaredType) subTypeMirror, executableElement);
+    TypeMirror subExecutableTypeMirror =
+        types.asMemberOf(MoreTypes.asDeclared(subTypeMirror), executableElement);
     if (!subExecutableTypeMirror.getKind().equals(TypeKind.EXECUTABLE)) {
       throw new IllegalStateException("Expected subExecutableTypeMirror to be an executable type.");
     }
-    return (ExecutableType) subExecutableTypeMirror;
+    return MoreTypes.asExecutable(subExecutableTypeMirror);
   }
 }
diff --git a/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptor.java b/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptor.java
index 5ed2307a..090ac27a 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptor.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptor.java
@@ -17,16 +17,15 @@ package com.google.auto.factory.processor;
 
 import com.google.auto.value.AutoValue;
 import com.google.common.base.CharMatcher;
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableBiMap;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Sets;
-import java.util.Collection;
+import com.google.common.collect.Streams;
 import java.util.HashSet;
-import java.util.Map.Entry;
+import java.util.Optional;
 import java.util.Set;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.type.TypeMirror;
@@ -60,7 +59,7 @@ abstract class FactoryDescriptor {
   }
 
   private static class UniqueNameSet {
-    private final Set<String> uniqueNames = new HashSet<String>();
+    private final Set<String> uniqueNames = new HashSet<>();
 
     /**
      * Generates a unique name using {@code base}. If {@code base} has not yet been added, it will
@@ -92,33 +91,37 @@ abstract class FactoryDescriptor {
     }
     ImmutableMap.Builder<Key, ProviderField> providersBuilder = ImmutableMap.builder();
     UniqueNameSet uniqueNames = new UniqueNameSet();
-    for (Entry<Key, Collection<Parameter>> entry :
-        parametersForProviders.build().asMap().entrySet()) {
-      Key key = entry.getKey();
-      switch (entry.getValue().size()) {
-        case 0:
-          throw new AssertionError();
-        case 1:
-          Parameter parameter = Iterables.getOnlyElement(entry.getValue());
-          providersBuilder.put(
-              key,
-              ProviderField.create(
-                  uniqueNames.getUniqueName(parameter.name() + "Provider"),
-                  key,
-                  parameter.nullable()));
-          break;
-        default:
-          String providerName =
-              uniqueNames.getUniqueName(
-                  invalidIdentifierCharacters.replaceFrom(key.toString(), '_') + "Provider");
-          Optional<AnnotationMirror> nullable = Optional.absent();
-          for (Parameter param : entry.getValue()) {
-            nullable = nullable.or(param.nullable());
-          }
-          providersBuilder.put(key, ProviderField.create(providerName, key, nullable));
-          break;
-      }
-    }
+    parametersForProviders
+        .build()
+        .asMap()
+        .forEach(
+            (key, parameters) -> {
+              switch (parameters.size()) {
+                case 0:
+                  throw new AssertionError();
+                case 1:
+                  Parameter parameter = Iterables.getOnlyElement(parameters);
+                  providersBuilder.put(
+                      key,
+                      ProviderField.create(
+                          uniqueNames.getUniqueName(parameter.name() + "Provider"),
+                          key,
+                          parameter.nullable()));
+                  break;
+                default:
+                  String providerName =
+                      uniqueNames.getUniqueName(
+                          invalidIdentifierCharacters.replaceFrom(key.toString(), '_')
+                              + "Provider");
+                  Optional<AnnotationMirror> nullable =
+                      parameters.stream()
+                          .map(Parameter::nullable)
+                          .flatMap(Streams::stream)
+                          .findFirst();
+                  providersBuilder.put(key, ProviderField.create(providerName, key, nullable));
+                  break;
+              }
+            });
 
     ImmutableBiMap<FactoryMethodDescriptor, ImplementationMethodDescriptor>
         duplicateMethodDescriptors =
@@ -129,8 +132,8 @@ abstract class FactoryDescriptor {
         getDeduplicatedMethodDescriptors(methodDescriptors, duplicateMethodDescriptors);
 
     ImmutableSet<ImplementationMethodDescriptor> deduplicatedImplementationMethodDescriptors =
-        ImmutableSet.copyOf(
-            Sets.difference(implementationMethodDescriptors, duplicateMethodDescriptors.values()));
+        Sets.difference(implementationMethodDescriptors, duplicateMethodDescriptors.values())
+            .immutableCopy();
 
     return new AutoValue_FactoryDescriptor(
         name,
diff --git a/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptorGenerator.java b/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptorGenerator.java
index d2331f42..4faa6e7a 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptorGenerator.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/FactoryDescriptorGenerator.java
@@ -18,6 +18,7 @@ package com.google.auto.factory.processor;
 import static com.google.auto.common.MoreElements.isAnnotationPresent;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.stream.Collectors.partitioningBy;
 import static javax.lang.model.element.Modifier.ABSTRACT;
 import static javax.lang.model.element.Modifier.PUBLIC;
 import static javax.tools.Diagnostic.Kind.ERROR;
@@ -26,13 +27,11 @@ import com.google.auto.common.MoreElements;
 import com.google.auto.factory.AutoFactory;
 import com.google.auto.factory.Provided;
 import com.google.common.base.Function;
-import com.google.common.base.Functions;
-import com.google.common.base.Optional;
-import com.google.common.base.Predicate;
 import com.google.common.collect.FluentIterable;
-import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Multimaps;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
 import javax.annotation.processing.Messager;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.Element;
@@ -107,8 +106,8 @@ final class FactoryDescriptorGenerator {
       }
 
       @Override
-      public ImmutableSet<FactoryMethodDescriptor> visitExecutableAsConstructor(ExecutableElement e,
-          Void p) {
+      public ImmutableSet<FactoryMethodDescriptor> visitExecutableAsConstructor(
+          ExecutableElement e, Void p) {
         // applied to a constructor of a type to be created
         return ImmutableSet.of(generateDescriptorForConstructor(declaration.get(), e));
       }
@@ -120,14 +119,9 @@ final class FactoryDescriptorGenerator {
     checkNotNull(constructor);
     checkArgument(constructor.getKind() == ElementKind.CONSTRUCTOR);
     TypeElement classElement = MoreElements.asType(constructor.getEnclosingElement());
-    ImmutableListMultimap<Boolean, ? extends VariableElement> parameterMap =
-        Multimaps.index(constructor.getParameters(), Functions.forPredicate(
-            new Predicate<VariableElement>() {
-              @Override
-              public boolean apply(VariableElement parameter) {
-                return isAnnotationPresent(parameter, Provided.class);
-              }
-            }));
+    Map<Boolean, List<VariableElement>> parameterMap =
+        constructor.getParameters().stream()
+            .collect(partitioningBy(parameter -> isAnnotationPresent(parameter, Provided.class)));
     ImmutableSet<Parameter> providedParameters =
         Parameter.forParameterList(parameterMap.get(true), types);
     ImmutableSet<Parameter> passedParameters =
@@ -150,9 +144,9 @@ final class FactoryDescriptorGenerator {
             .name("create")
             .returnType(type.asType())
             .publicMethod(type.getModifiers().contains(PUBLIC))
-            .passedParameters(ImmutableSet.<Parameter>of())
-            .creationParameters(ImmutableSet.<Parameter>of())
-            .providedParameters(ImmutableSet.<Parameter>of())
+            .passedParameters(ImmutableSet.of())
+            .creationParameters(ImmutableSet.of())
+            .providedParameters(ImmutableSet.of())
             .build());
   }
 }
diff --git a/factory/src/main/java/com/google/auto/factory/processor/FactoryWriter.java b/factory/src/main/java/com/google/auto/factory/processor/FactoryWriter.java
index 53b99cb5..b1ba2f18 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/FactoryWriter.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/FactoryWriter.java
@@ -19,19 +19,18 @@ import static com.google.auto.common.GeneratedAnnotationSpecs.generatedAnnotatio
 import static com.squareup.javapoet.MethodSpec.constructorBuilder;
 import static com.squareup.javapoet.MethodSpec.methodBuilder;
 import static com.squareup.javapoet.TypeSpec.classBuilder;
+import static java.util.stream.Collectors.joining;
 import static javax.lang.model.element.Modifier.FINAL;
 import static javax.lang.model.element.Modifier.PRIVATE;
 import static javax.lang.model.element.Modifier.PUBLIC;
 import static javax.lang.model.element.Modifier.STATIC;
 
-import com.google.common.base.Function;
-import com.google.common.base.Joiner;
-import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Sets;
+import com.google.common.collect.Streams;
 import com.squareup.javapoet.AnnotationSpec;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.CodeBlock;
@@ -44,12 +43,12 @@ import com.squareup.javapoet.TypeSpec;
 import com.squareup.javapoet.TypeVariableName;
 import java.io.IOException;
 import java.util.Iterator;
+import java.util.stream.Stream;
 import javax.annotation.processing.Filer;
 import javax.annotation.processing.ProcessingEnvironment;
 import javax.inject.Inject;
 import javax.inject.Provider;
 import javax.lang.model.SourceVersion;
-import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
 import javax.lang.model.type.TypeVariable;
@@ -71,8 +70,6 @@ final class FactoryWriter {
     this.factoriesBeingCreated = factoriesBeingCreated;
   }
 
-  private static final Joiner ARGUMENT_JOINER = Joiner.on(", ");
-
   void writeFactory(FactoryDescriptor descriptor)
       throws IOException {
     String factoryName = descriptor.name().className();
@@ -205,15 +202,7 @@ final class FactoryWriter {
       implementationMethod.addParameters(parameters(methodDescriptor.passedParameters()));
       implementationMethod.addStatement(
           "return create($L)",
-          FluentIterable.from(methodDescriptor.passedParameters())
-              .transform(
-                  new Function<Parameter, String>() {
-                    @Override
-                    public String apply(Parameter parameter) {
-                      return parameter.name();
-                    }
-                  })
-              .join(ARGUMENT_JOINER));
+          methodDescriptor.passedParameters().stream().map(Parameter::name).collect(joining(", ")));
       factory.addMethod(implementationMethod.build());
     }
   }
@@ -227,10 +216,10 @@ final class FactoryWriter {
     for (Parameter parameter : parameters) {
       ParameterSpec.Builder parameterBuilder =
           ParameterSpec.builder(resolveTypeName(parameter.type().get()), parameter.name());
-      for (AnnotationMirror annotation :
-          Iterables.concat(parameter.nullable().asSet(), parameter.key().qualifier().asSet())) {
-        parameterBuilder.addAnnotation(AnnotationSpec.get(annotation));
-      }
+      Stream.of(parameter.nullable(), parameter.key().qualifier())
+          .flatMap(Streams::stream)
+          .map(AnnotationSpec::get)
+          .forEach(parameterBuilder::addAnnotation);
       builder.add(parameterBuilder.build());
     }
     return builder.build();
diff --git a/factory/src/main/java/com/google/auto/factory/processor/ImplementationMethodDescriptor.java b/factory/src/main/java/com/google/auto/factory/processor/ImplementationMethodDescriptor.java
index 9ddc249f..b7367a6c 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/ImplementationMethodDescriptor.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/ImplementationMethodDescriptor.java
@@ -34,9 +34,9 @@ abstract class ImplementationMethodDescriptor {
   }
 
   @AutoValue.Builder
-  static abstract class Builder {
+  abstract static class Builder {
     abstract Builder name(String name);
-    
+
     abstract Builder returnType(TypeMirror returnTypeElement);
 
     abstract Builder publicMethod(boolean publicMethod);
diff --git a/factory/src/main/java/com/google/auto/factory/processor/Key.java b/factory/src/main/java/com/google/auto/factory/processor/Key.java
index 04bd4f37..12cfd927 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/Key.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/Key.java
@@ -24,9 +24,8 @@ import com.google.auto.common.AnnotationMirrors;
 import com.google.auto.common.MoreTypes;
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Equivalence;
-import com.google.common.base.Optional;
-import com.google.common.collect.FluentIterable;
-import com.google.common.collect.ImmutableSet;
+import java.util.Collection;
+import java.util.Optional;
 import javax.inject.Qualifier;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.type.TypeMirror;
@@ -65,17 +64,13 @@ abstract class Key {
    *   <tr><td>{@code int}               <td>{@code Integer}
    * </table>
    */
-  static Key create(
-      TypeMirror type, Iterable<? extends AnnotationMirror> annotations, Types types) {
-    ImmutableSet.Builder<AnnotationMirror> qualifiers = ImmutableSet.builder();
-    for (AnnotationMirror annotation : annotations) {
-      if (isAnnotationPresent(annotation.getAnnotationType().asElement(), Qualifier.class)) {
-        qualifiers.add(annotation);
-      }
-    }
-
+  static Key create(TypeMirror type, Collection<AnnotationMirror> annotations, Types types) {
     // TODO(gak): check for only one qualifier rather than using the first
-    Optional<AnnotationMirror> qualifier = FluentIterable.from(qualifiers.build()).first();
+    Optional<AnnotationMirror> qualifier =
+        annotations.stream()
+            .filter(annotation ->
+                isAnnotationPresent(annotation.getAnnotationType().asElement(), Qualifier.class))
+            .findFirst();
 
     TypeMirror keyType =
         isProvider(type)
@@ -97,7 +92,7 @@ abstract class Key {
   }
 
   @Override
-  public String toString() {
+  public final String toString() {
     String typeQualifiedName = MoreTypes.asTypeElement(type().get()).toString();
     return qualifier().isPresent()
         ? qualifier().get() + "/" + typeQualifiedName
diff --git a/factory/src/main/java/com/google/auto/factory/processor/Mirrors.java b/factory/src/main/java/com/google/auto/factory/processor/Mirrors.java
index c5b7d8bf..9e111875 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/Mirrors.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/Mirrors.java
@@ -17,11 +17,11 @@ package com.google.auto.factory.processor;
 
 import com.google.auto.common.MoreTypes;
 import com.google.common.base.Equivalence;
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableMap;
 import java.lang.annotation.Annotation;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Optional;
 import javax.inject.Provider;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.AnnotationValue;
@@ -76,12 +76,11 @@ final class Mirrors {
   static Optional<AnnotationMirror> getAnnotationMirror(Element element,
       Class<? extends Annotation> annotationType) {
     String annotationName = annotationType.getName();
-    for (AnnotationMirror annotationMirror : element.getAnnotationMirrors()) {
-      if (getQualifiedName(annotationMirror.getAnnotationType()).contentEquals(annotationName)) {
-        return Optional.of(annotationMirror);
-      }
-    }
-    return Optional.absent();
+    return element.getAnnotationMirrors().stream()
+        .filter(
+            a -> getQualifiedName(a.getAnnotationType()).contentEquals(annotationName))
+        .<AnnotationMirror>map(x -> x) // get rid of wildcard <? extends AnnotationMirror>
+        .findFirst();
   }
 
   /**
@@ -91,9 +90,7 @@ final class Mirrors {
   // TODO(ronshapiro): this is used in AutoFactory and Dagger, consider moving it into auto-common.
   static <T> Optional<Equivalence.Wrapper<T>> wrapOptionalInEquivalence(
       Equivalence<T> equivalence, Optional<T> optional) {
-    return optional.isPresent()
-        ? Optional.of(equivalence.wrap(optional.get()))
-        : Optional.<Equivalence.Wrapper<T>>absent();
+    return optional.map(equivalence::wrap);
   }
 
   /**
@@ -102,8 +99,6 @@ final class Mirrors {
    */
   static <T> Optional<T> unwrapOptionalEquivalence(
       Optional<Equivalence.Wrapper<T>> wrappedOptional) {
-    return wrappedOptional.isPresent()
-        ? Optional.of(wrappedOptional.get().get())
-        : Optional.<T>absent();
+    return wrappedOptional.map(Equivalence.Wrapper::get);
   }
 }
diff --git a/factory/src/main/java/com/google/auto/factory/processor/Parameter.java b/factory/src/main/java/com/google/auto/factory/processor/Parameter.java
index 781225a2..57660e0d 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/Parameter.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/Parameter.java
@@ -18,19 +18,20 @@ package com.google.auto.factory.processor;
 import static com.google.auto.factory.processor.Mirrors.unwrapOptionalEquivalence;
 import static com.google.auto.factory.processor.Mirrors.wrapOptionalInEquivalence;
 import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.stream.Collectors.toList;
 
 import com.google.auto.common.AnnotationMirrors;
 import com.google.auto.common.MoreElements;
 import com.google.auto.common.MoreTypes;
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Equivalence;
-import com.google.common.base.Optional;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import java.util.List;
+import java.util.Optional;
 import java.util.Set;
+import java.util.stream.Stream;
 import javax.inject.Provider;
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.TypeElement;
@@ -71,15 +72,12 @@ abstract class Parameter {
 
   private static Parameter forVariableElement(
       VariableElement variable, TypeMirror type, Types types) {
-    Optional<AnnotationMirror> nullable = Optional.absent();
-    Iterable<? extends AnnotationMirror> annotations =
-        Iterables.concat(variable.getAnnotationMirrors(), type.getAnnotationMirrors());
-    for (AnnotationMirror annotation : annotations) {
-      if (isNullable(annotation)) {
-        nullable = Optional.of(annotation);
-        break;
-      }
-    }
+    List<AnnotationMirror> annotations =
+        Stream.of(variable.getAnnotationMirrors(), type.getAnnotationMirrors())
+            .flatMap(List::stream)
+            .collect(toList());
+    Optional<AnnotationMirror> nullable =
+        annotations.stream().filter(Parameter::isNullable).findFirst();
 
     Key key = Key.create(type, annotations, types);
     return new AutoValue_Parameter(
diff --git a/factory/src/main/java/com/google/auto/factory/processor/ProviderField.java b/factory/src/main/java/com/google/auto/factory/processor/ProviderField.java
index 855c1feb..f18def32 100644
--- a/factory/src/main/java/com/google/auto/factory/processor/ProviderField.java
+++ b/factory/src/main/java/com/google/auto/factory/processor/ProviderField.java
@@ -21,7 +21,7 @@ import static com.google.auto.factory.processor.Mirrors.wrapOptionalInEquivalenc
 import com.google.auto.common.AnnotationMirrors;
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Equivalence;
-import com.google.common.base.Optional;
+import java.util.Optional;
 import javax.lang.model.element.AnnotationMirror;
 
 @AutoValue