* refactor how we use connection and async connection to rely on their access methods * refactor initialization and cleanup of the shared connection * incompatibly change HCTU's Configuration member variable to be final so it can be safely accessed from multiple threads. Closes #2180 Signed-off-by: Wellington Chevreuil <wchevreuil@apache.org> Signed-off-by: Viraj Jasani <vjasani@apache.org>