docs: private void init() {
          cacheable = null;
          status = SC_OK;
          cachedResponse = cached.createCachedResponse();
          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 cachedResponse.getOutputStream();
                  }
                  else {
                      cachedResponse.setStatus(status);
                      cachedResponse.writeHeadersTo(CacheResponseWrapper.this.response);
                      return super.getOutputStream();
                  }
              }
          };
      }