@ApiStatus.Experimental
  default boolean isUnnamed() {
    return "_".equals(getName()) &&
           !(this instanceof PsiCompiledElement) &&
           // Treat _ as unsupported unnamed variable since JDK 1.9, 
           // so we can get a proper suggestion to update language level
           PsiUtil.getLanguageLevel(this).isAtLeast(LanguageLevel.JDK_1_9);
  }
@ApiStatus.Experimental
  default boolean isUnnamed()