@NotNull
  @Override
  public InputFilter getInputFilter() {
    return new DefaultFileTypeSpecificInputFilter(JavaClassFileType.INSTANCE) {
      @Override
      public boolean acceptInput(@NotNull VirtualFile file) {
        return StringUtil.endsWith(file.getNameSequence(), HELPER_SUFFIX);
      }
    };
  }
@NotNull
  @Override
  public InputFilter getInputFilter()