docs: private void init() {
          cacheable = null;
          status = SC_OK;
          streamDelegate = new ServletResponseStreamDelegate(this) {
              protected OutputStream createOutputStream() throws IOException {
                  // Test if this request is really cacheable, otherwise,
                  // just write through to underlying response, and don't cache
                  if (isCacheable()) {
                      return cacheResponse.getOutputStream();
                  }
                  else {
                      // TODO: We need to tell the cache about this, somehow...
                      writeHeaders(cacheResponse, (HttpServletResponse) getResponse());
                      return super.getOutputStream();
                  }
              }
          };
      }