protected static @Nullable PsiElement findTrailingComma(@NotNull PsiElement lastChild, @NotNull IElementType ending) {
    if (lastChild.getNode().getElementType() != ending) {
      return null;
    }
    final PsiElement beforeEnding = PsiTreeUtil.skipWhitespacesAndCommentsBackward(lastChild);
    if (beforeEnding != null && beforeEnding.getNode().getElementType() == JsonElementTypes.COMMA) {
      return beforeEnding;
    }
    return null;
  }
protected static @Nullable PsiElement findTrailingComma(@NotNull PsiElement lastChild, @NotNull IElementType ending)