docs: function (args) {
          if (typeof(args.value) != 'string') {
              return __badTypeError(this, args); // this refers to the correct object (a base type)
          }
          var beanDef = args.beanDef;
          while (!beanDef[jv._MD_BUILTIN]) {
              var regexp = beanDef.$regExp;
              if (regexp != null) {
                  if (!regexp.test(args.value)) {
                      return jv._logError(jv.REGEXP_FAILED, [args.value, args.path, regexp, beanDef[jv._MD_TYPENAME]]);
                  }
              }
              beanDef = beanDef[jv._MD_PARENTDEF];
          }
      }