Creating new object using an existing object with HandlerInterceptorAdapter

I wanted all my exceptions to be logged. I thought thought that adding Logger.error to every method would solve my problem, but luckily I discovered HandlerInterceptorAdapter and saved time!

Now I don't want to return "regular" objects, but to return an object that contains other objects and exceptions. The reason is that in this way, I won't get HTTP Status 500, but get an object containing the exception.

Basically: If my service would return normally - return an object containing the returned object.

If my service would return with an exception - return an object that has the children up to the exception, and the exception that caused the problem.

I hoped that using HandlerInterceptorAdapter would be easy, but I was mistaken...

In a regular service - If I look at postHandle: modelAndView is null.

In both postHandle and afterCompletion using response.getWriter().write(s) raises

SEVERE: Servlet.service() for servlet [appServlet] threw exception 
java.lang.IllegalStateException: getOutputStream() has already been called for this response

response.getHeaderNames() contains only [Content-Type, Transfer-Encoding, Date].

I don't know what to do with response.getOutputStream().

Using request/handler gets me to no where also.

What can I do?