@VisibleForTesting
  static String parseAcceptHeader(HttpServletRequest request) {
    String format = request.getHeader(HttpHeaders.ACCEPT);
    return format != null && format.contains(FORMAT_JSON) ?
        FORMAT_JSON : FORMAT_XML;
  }
@Test
  public void testParseHeaders() throws Exception {
    HashMap<String, String> verifyMap = new HashMap<String, String>();
    verifyMap.put("text/plain", ConfServlet.FORMAT_XML);
    verifyMap.put(null, ConfServlet.FORMAT_XML);
    verifyMap.put("text/xml", ConfServlet.FORMAT_XML);
    verifyMap.put("application/xml", ConfServlet.FORMAT_XML);
    verifyMap.put("application/json", ConfServlet.FORMAT_JSON);

    HttpServletRequest request = Mockito.mock(HttpServletRequest.class);
    for(String contentTypeExpected : verifyMap.keySet()) {
      String contenTypeActual = verifyMap.get(contentTypeExpected);
      Mockito.when(request.getHeader(HttpHeaders.ACCEPT))
          .thenReturn(contentTypeExpected);
      assertEquals(contenTypeActual,
          ConfServlet.parseAcceptHeader(request));
    }
  }