@Test
  public void backPressureTest() throws Exception {
    String[] digestAlgorithms = {"", "MD5", "SHA-1", "SHA-256"};

    HttpMethod[] methods = {HttpMethod.POST, HttpMethod.PUT};
    for (HttpMethod method : methods) {
      for (String digestAlgorithm : digestAlgorithms) {
        backPressureTest(digestAlgorithm, true, method);
        backPressureTest(digestAlgorithm, false, method);
      }
    }
  }
Tests {@link NettyRequest#addContent(HttpContent)} and
{@link NettyRequest#readInto(AsyncWritableChannel, Callback)} with different digest algorithms (including a test
with no digest algorithm) and checks that back pressure is applied correctly.
@throws Exception
ambry-rest/src/test/java/com/github/ambry/rest/NettyRequestTest.java