diff --git a/code_samples/tree_structure_provider/src/main/java/org/jetbrains/tutorials/tree/structure/TextOnlyTreeStructureProvider.java b/code_samples/tree_structure_provider/src/main/java/org/jetbrains/tutorials/tree/structure/TextOnlyTreeStructureProvider.java
index 8f842be82..3f4dc0b59 100644
--- a/code_samples/tree_structure_provider/src/main/java/org/jetbrains/tutorials/tree/structure/TextOnlyTreeStructureProvider.java
+++ b/code_samples/tree_structure_provider/src/main/java/org/jetbrains/tutorials/tree/structure/TextOnlyTreeStructureProvider.java
@@ -33,7 +33,7 @@ public class TextOnlyTreeStructureProvider implements TreeStructureProvider {
 
   @Nullable
   @Override
-  public Object getData(Collection<AbstractTreeNode> collection, String s) {
+  public Object getData(@NotNull Collection<AbstractTreeNode> selected, @NotNull String dataId) {
     return null;
   }
 }
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