make TreeStructureProvider#getData default

java/java-tests/testSrc/com/intellij/projectView/SameNamesJoiner.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -67,11 +67,6 @@ class SameNamesJoiner implements TreeStructureProvider {
     return result;
   }
 
-  @Override
-  public Object getData(Collection<AbstractTreeNode> selected, String dataName) {
-    return null;
-  }
-
   public PsiElement getTopLevelElement(final PsiElement element) {
     return null;
   }