private static boolean isAppendCall(PsiElement element) {
    if (!(element instanceof PsiMethodCallExpression methodCallExpression)) {
      return false;
    }
    if (STRING_JOINER_ADD.test(methodCallExpression)) return true;
    final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
    final @NonNls String methodName = methodExpression.getReferenceName();
    if (!"append".equals(methodName)) {
      return false;
    }
    final PsiExpressionList argumentList = methodCallExpression.getArgumentList();
    final PsiExpression[] arguments = argumentList.getExpressions();
    if (arguments.length == 3) {
      return (arguments[0].getType() instanceof PsiArrayType || TypeUtils.isJavaLangString(arguments[0].getType())) &&
             PsiTypes.intType().equals(arguments[1].getType()) && PsiTypes.intType().equals(arguments[2].getType());
    }
    return arguments.length == 1;
  }
private static boolean isAppendCall(PsiElement element)