public static boolean isCaseNull(@Nullable PsiSwitchLabelStatementBase label) {
    if (label == null) return false;
    PsiCaseLabelElementList labelElementList = label.getCaseLabelElementList();
    return labelElementList != null &&
           labelElementList.getElementCount() == 1 &&
           labelElementList.getElements()[0] instanceof PsiExpression expr &&
           ExpressionUtils.isNullLiteral(expr);
  }
public static boolean isCaseNull(@Nullable PsiSwitchLabelStatementBase label)