code: @Override
      public String parameter(String name, String defaultValue) {
          String v = request.params().get(name);
          return v != null ? v : defaultValue;
      }
docs: Same like {@link #parameter(String)}, but returns given defaultValue
  instead of null in case parameter cannot be found.
  <p/>
  The parameter is decoded by default.
  
  @param name         The name of the post or query parameter
  @param defaultValue A default value if parameter not found.
  @return The value of the parameter of the defaultValue if not found.