* refactor how we use connection to rely on the access method
* 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#2188
adapted for jdk7
Signed-off-by: Viraj Jasani <vjasani@apache.org>
(cherry picked from commit 86ebbdd8a2df89de37c2c3bd50e64292eaf28b11)
(cherry picked from commit 0806349adab338330428c900588234d7f6fcfcc2)