code: public static void validateArgument(Method method, Class<? extends Annotation> annotationType,
                                          Class<?> expectedParameterType) {
          if (method.getParameterTypes().length != 1 || !method.getParameterTypes()[0].equals(expectedParameterType)) {
              throw new BeanCreationException(String.format(
                    "Method %s with @%s MUST take a single argument of type %s",
                    method,
                    annotationType.getName(),
                    expectedParameterType.getName()
              ));
          }
      }
docs: Validates that the method annotated with the specified annotation has a single
  argument of the expected type.