@Test
  public void numberHeader() throws Exception {
    final AtomicReference<String> h1 = new AtomicReference<String>();
    final AtomicReference<String> h2 = new AtomicReference<String>();
    handler = new RequestHandler() {

      @Override
      public void handle(Request request, HttpServletResponse response) {
        response.setStatus(HTTP_OK);
        h1.set(request.getHeader("h1"));
        h2.set(request.getHeader("h2"));
      }
    };
    assertTrue(get(url).header("h1", 5).header("h2", (Number) null).ok());
    assertEquals("5", h1.get());
    assertEquals("", h2.get());
  }
Verify setting number header

@throws Exception
lib/src/test/java/com/github/kevinsawicki/http/HttpRequestTest.java