@Override
    public @Nullable Set<VirtualFile> findReferentFileIds(@NotNull CompilerRef ref, boolean checkBaseClassAmbiguity) throws StorageException {
      CompilerRef.NamedCompilerRef[] hierarchy;
      if (ref instanceof CompilerRef.CompilerClassHierarchyElementDef) {
        hierarchy = new CompilerRef.NamedCompilerRef[]{(CompilerRef.NamedCompilerRef)ref};
      }
      else {
        CompilerRef.CompilerClassHierarchyElementDef hierarchyElement = ((CompilerRef.CompilerMember)ref).getOwner();
        hierarchy = getHierarchy(hierarchyElement, checkBaseClassAmbiguity, false, -1);
      }
      if (hierarchy == null) return null;
      Set<VirtualFile> set = VfsUtilCore.createCompactVirtualFileSet();
      for (CompilerRef.NamedCompilerRef aClass : hierarchy) {
        final CompilerRef overriderUsage = ref.override(aClass.getName());
        addUsages(overriderUsage, set);
      }
      return set;
    }
@Override
    public @Nullable Set<VirtualFile> findReferentFileIds(@NotNull CompilerRef ref, boolean checkBaseClassAmbiguity)