What does "HttpServletResponse is committed" mean?
<p>As stated in title, what does it mean that HttpServletResponse is committed?</p>

<p>I have some request interceptor, extending <code>HandlerInterceptorAdapter</code>, that overrides <code>postHandle</code> method. Post handle method takes parameter <code>final HttpServletResponse response</code>. In method body there is an <code>if</code> statement checking if <code>response.isCommitted()</code>, what exactly does that check?</p>

<pre><code>private static final String voidResponse = "null";

@Override
    public void postHandle(final HttpServletRequest request, final HttpServletResponse response, final Object handler,
            final ModelAndView modelAndView) throws IOException {
        if (!response.isCommitted()) {
            if (DefaultServletHttpRequestHandler.class == handler.getClass()) {
                return;
            }
            response.setStatus(200);
            response.setCharacterEncoding("UTF-8");
            response.setContentType("application/json");
            try (final Writer writer = response.getWriter()) {
                writer.write(voidResponse);
            }
            log.info("void method called, respond with 200 and null");

            response.flushBuffer();
        }
    }
</code></pre>