code: public static ResolvableType forMethodReturnType(Method method) {
          LettuceAssert.notNull(method, "Method must not be null");
          return forMethodParameter(new MethodParameter(method, -1));
      }
docs: Return a {@link ResolvableType} for the specified {@link Method} return type.
  
  @param method the source for the method return type
  @return a {@link ResolvableType} for the specified method return
  @see #forMethodReturnType(Method, Class)