code: @PostMapping(
        value = "/{entityTypeId}/meta/{attributeName}",
        params = "_method=GET",
        produces = APPLICATION_JSON_VALUE)
    public AttributeResponse retrieveEntityAttributeMetaPost(
        @PathVariable("entityTypeId") String entityTypeId,
        @PathVariable("attributeName") String attributeName,
        @Valid @RequestBody EntityTypeRequest request) {
      Set<String> attributeSet = toAttributeSet(request != null ? request.getAttributes() : null);
      Map<String, Set<String>> attributeExpandSet =
          toExpandMap(request != null ? request.getExpand() : null);
  
      return getAttributePostInternal(entityTypeId, attributeName, attributeSet, attributeExpandSet);
    }
docs: Same as retrieveEntityAttributeMeta (GET) only tunneled through POST.
  
  @return EntityType