ServletResponse.setBufferSize not working in Tomcat 7?

I am increasing the size of the response buffer with ServletResponse.setBufferSize, but Tomcat 7 still throws an exception that the buffer size is not large enough. Is this a bug in Tomcat 7.0.32?

Here is my pseudo / code -

@Override
protected void writeInternal(Object o, HttpOutputMessage outputMessage)
    throws IOException, HttpMessageNotWritableException {

    if (some condition)
    {
        ((ServletServerHttpResponse)outputMessage).getServletResponse().setBufferSize(Integer.MAX_VALUE);
        outputMessage.getHeaders().set("Custom-Header", gson.toJson(big payload));
    }

    // ...

This is an exception -

org.apache.coyote.http11.HeadersTooLargeException: An attempt was made to write more data to the response headers than there was a place in the buffer. Increase maxHttpHeaderSize on the connector or write less data in the response headers.

Do I need to reset the buffer? reset()does not work.

EDIT: I'm looking for an opportunity to change the maximum header size at the individual response level based on "some state".