code: public Box<Object> out(Object key, int type, String struct,
              Converter decoder) {
          Parameter parameter = new Parameter();
          parameter.setOutput(new Box<Object>());
          parameter.setType(type);
          parameter.setStruct(struct);
          parameter.setDecoder(decoder);
          return merge(key, parameter).getOutput();
      }
docs: Registers an output parameter with specified key.
  
  @param key subroutine parameter key.
  @param type subroutine parameter SQL type code.
  @param struct a name of parameter structured type (optional).
  @param decoder a converter for SQL data decoding (optional).
  @return an output value container.
  
  @see Box
  @see Converter
  
  @since v1.0