UserIdMDCPutFilter extends AbstractMDCPutFilter { @Override protected String getMDCKey(HttpServletRequest request, HttpServletResponse response) { return attributeName; }  void setAttributeName(String attibuteName);  }
@Test public void testGetMDCKey() { UserIdMDCPutFilter mdcPutFilter = new UserIdMDCPutFilter(); String mdcKeyStr = mdcPutFilter.getMDCKey(request, response); assertThat(mdcKeyStr, is("USER")); }