code: function (parameters, result) {
                  var
                      len,
                      idx,
                      parameter,
                      name,
                      value;
                  len = parameters.length;
                  for (idx = 0; idx < len; ++idx) {
                      parameter = parameters[idx];
                      name = parameter._name;
                      if (undefined === result[name]) {
                          if (parameter._required) {
                              gpf.Error.paramsRequiredMissing({
                                  name: name
                              });
                          }
                          value = parameter._defaultValue;
                          if (undefined !== value) {
                              if (parameter._multiple) {
                                  value = [value];
                              }
                              result[name] = value;
                          } else if (parameter._multiple) {
                              result[name] = [];
                          }
                      }
                  }
              }
docs: Check that all required fields are set,
  apply default values
  
  @param {gpf.Parameter[]} parameters
  @param {Object} result
  @private