code: @Override
      public String parameter(String name) {
          String s = request.params().get(name);
          if (s == null) {
              // Check form parameter
              if (formData != null) {
                  List<String> l = formData.get(name);
                  if (l != null && !l.isEmpty()) {
                      return l.get(0);
                  }
              }
              return null;
          } else {
              return s;
          }
      }
docs: Get the parameter with the given key from the request. The parameter may
  either be a query parameter, or in the case of form submissions, may be a
  form parameter.
  <p/>
  When the parameter is multivalued, returns the first value.
  <p/>
  The parameter is decoded by default.
  
  @param name The key of the parameter
  @return The value, or null if no parameter was found.
  @see #parameterMultipleValues