code: public RESTParameter add(String childParamName, String childParamType) {
          return add(new RESTParameter(childParamName, childParamType));
      }
docs: Add a new child parameter with the given name and type to this parameter. The child
  parameter will not be marked as required. This parameter is returned to support
  builder syntax.
  
  @param childParamName    Name of new child parameter.
  @param childParamType    Type of new child parameter.
  @return                  This parameter object.