code: private function isSimplePhpType(\stdClass $meta)
      {
          $phpTypes = explode('|', $meta->phpType);
  
          foreach ($phpTypes as $phpType) {
              switch ($phpType) {
                  case 'integer':
                  case 'string':
                  case 'double':
                  case 'boolean':
                  case 'DateTime':
                      continue;
                  default:
                      return false;
              }
          }
  
          return true;
      }
docs: Determines if the type of the property is simple.
  
  @param \stdClass $meta The PHP meta data.
  
  @return bool True if the property type is simple.