code: function (preconditions) {
          var errorCodesList = {
              "500": ["InternalServerError"],
              "400": [
                  "UnexpectedDefaultValue",
                  "UnexpectedType",
                  "MinLengthUnderachieved",
                  "MaxLengthExceeded",
                  "MinValueUnderachived",
                  "MaxValueExceeded",
                  "ValueNotAllowed",
                  "PatternMismatch",
                  "MissingRequiredParameter"],
              "429": ["RateLimitExceeded"],
          };
          for (var index in preconditions) {
              if (preconditions[index].conditions && preconditions[index].conditions.responses) {
                  for (var code in preconditions[index].conditions.responses) {
                      if (errorCodesList[code]) {
                          if (_.isArray(preconditions[index].conditions.responses[code])) {
                              for (var ecode in preconditions[index].conditions.responses[code]) {
                                  if (_.indexOf(errorCodesList[code], preconditions[index].conditions.responses[code][ecode]) == -1) {
                                      errorCodesList[code].push(preconditions[index].conditions.responses[code][ecode]);
                                  }
                              }
                          }
                          else {
                              if (_.indexOf(errorCodesList[code], preconditions[index].conditions.responses[code]) == -1) {
                                  errorCodesList[code].push(preconditions[index].conditions.responses[code]);
                              }
                          }
                      }
                      else {
                          if (_.isArray(preconditions[index].conditions.responses[code])) {
                              errorCodesList[code] = _.clone(preconditions[index].conditions.responses[code]);
                          }
                          else {
                              errorCodesList[code] = [_.clone(preconditions[index].conditions.responses[code])];
                          }
                      }
                  }
              }
          }
          return errorCodesList;
      }
docs: Returns a list of http codes defined in preconditions section in controller