@Test
  public void testUnknownAttributeIsNull() throws Exception {
    Callback c = (request, response) -> {
      Object o = request.getSession().getAttribute("unknown");
      PrintWriter out = response.getWriter();
      if (o == null) {
        out.write("null");
      } else {
        out.write(o.toString());
      }
    };

    tester.setAttribute("callback_1", c);
    tester.start();

    request.setMethod("GET");
    request.setURI("/test/hello");
    request.setHeader("Host", "tester");
    request.setVersion("HTTP/1.0");

    response = HttpTester.parseResponse(tester.getResponses(request.generate()));

    assertEquals("Unknown attribute should be null", "null", response.getContent());
  }
Test that getSession(false) does not create a new session
extensions/geode-modules-session/src/integrationTest/java/org/apache/geode/modules/session/internal/filter/SessionReplicationIntegrationJUnitTest.java