code: public static function getAllBuiltInTypes()
      {
          if (self::$builtInTypes === null) {
              self::$builtInTypes = array_merge(
                  Introspection::getTypes(),
                  self::getStandardTypes()
              );
          }
  
          return self::$builtInTypes;
      }
docs: Returns all builtin in types including base scalar and
  introspection types
  
  @return Type[]