v0.5.1(Not Apache release)

• [#774] support Etcd3 registration center
• [#793] support sofa-registry registration center
• [#856] add batch delete undolog processing
• [#786] support for branch transaction concurrency in global transactions
• [#945] add the releaseLock method in the LockManager interface to optimize the calling logic
• [#879] fix when batch delete undolog,the preparedStatement does not close
• [#921] fix NPE exception when select for update
• [#907] fix hostname can't be null exception
• [#923] fix the problem that the key is not formatted when the nettyClientKeyPool connection is destroyed.
• [#891] fix the NPE exception when using select union all
• [#888] fix copyright checkstyle verification
• [#901] fix parent node path does not exist when Zookeeper is registered
• [#866] fix unable to generate dubbo:reference proxy class
• [#877] fix concurrentModifyException when batch deleting undolog
• [#875] fix select for update, Boolean cast ResultSet failed
• [#830] fix RM late registration problem
• [#872] fix RegisterRMRequest decoding message length check is not accurate
• [#834] fix non-SQLException in ExecuteTemplate does not throw a exception
• [#938] optimize the TransactionManager service loading logic
• [#913] optimize the module structure of the RPC integration framework
• [#795] optimize the performance of server node write files
• [#925] optimize the same DefaultCoordinator instance when the server starts
• [#930] optimize field access modifiers
• [#904] optimize updated data query logic in UpdateExecutort
• [#802] optimize checkstyle and add plugins
• [#855] optimize the globalCommit always returns committed to the user in AT mode
• [#831] optimize CountDownLatch in MessageFuture and replace it with CompletableFuture
• [#882] modify copyright, add copyright automatic plugin
• [#874] add the communication default configuration value