code: public OptionalThing<String> extractRestfulHttpMethod(Method executeMethod) {
          final String methodName = executeMethod.getName();
          final String extracted = methodName.contains(REST_DELIMITER) ? Srl.substringFirstFront(methodName, REST_DELIMITER) : null;
          return OptionalThing.ofNullable(extracted, () -> {
              throw new IllegalStateException("Not found RESTful HTTP method: " + toSimpleMethodExp(executeMethod));
          });
      }
docs: =======