code: @Test public void put_requestHeadersPartlyUnavailable() throws Exception {
    final URL serverUrl=configureServer(new MockResponse());
    ResponseCache responseCache=new NoOpResponseCache(){
      @Override public CacheRequest put(    URI uri,    URLConnection urlConnection) throws IOException {
        try {
          urlConnection.getRequestProperties();
          fail();
        }
   catch (      UnsupportedOperationException expected) {
        }
        assertEquals("value",urlConnection.getRequestProperty("key"));
        return null;
      }
    }
  ;
    client.setResponseCache(responseCache);
    connection=client.open(serverUrl);
    connection.setRequestProperty("key","value");
    executeGet(connection);
  }
  