Allows to manage communications blocking.
XEP related: XEP-0191
BlockingCommandManager blockingCommandManager = BlockingCommandManager.getInstanceFor(connection);
boolean isSupported = blockingCommandManager.isSupportedByServer();
List<Jid> blockList = blockingCommandManager.getBlockList();
blockingCommandManager.blockContact(jid);
jid is a Jid
blockingCommandManager.unblockContact(jid);
jid is a Jid
blockingCommandManager.unblockAll();
BlockedErrorExtension.isInside(message));
message is a Message