1 files changed, 3 insertions, 2 deletions
diff --git a/python/edu/learn-python/src/com/jetbrains/python/edu/actions/StudyPreviousStudyTaskAction.java b/python/edu/learn-python/src/com/jetbrains/python/edu/actions/StudyPreviousStudyTaskAction.java
index bc26c28cfabd..f6da6a067894 100644
--- a/python/edu/learn-python/src/com/jetbrains/python/edu/actions/StudyPreviousStudyTaskAction.java
+++ b/python/edu/learn-python/src/com/jetbrains/python/edu/actions/StudyPreviousStudyTaskAction.java
@@ -3,13 +3,14 @@ package com.jetbrains.python.edu.actions;
 
 import com.jetbrains.python.edu.editor.StudyEditor;
 import com.jetbrains.python.edu.course.Task;
+import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
 
 public class StudyPreviousStudyTaskAction extends StudyTaskNavigationAction {
 
   @Override
-  protected JButton getButton(StudyEditor selectedStudyEditor) {
+  protected JButton getButton(@NotNull final StudyEditor selectedStudyEditor) {
     return selectedStudyEditor.getPrevTaskButton();
   }
 
@@ -19,7 +20,7 @@ public class StudyPreviousStudyTaskAction extends StudyTaskNavigationAction {
   }
 
   @Override
-  protected Task getTargetTask(Task sourceTask) {
+  protected Task getTargetTask(@NotNull final Task sourceTask) {
     return sourceTask.prev();
   }
 }
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