reduce collection instances while generating metrics

Besides 500, other errors indicate that the server is having problems,
so close the connection to avoid sending requests to the same bad
server.  DefaultKeepAliveStrategy will look at the request and response
headers for other reasons to close, such as "Connection: close" headers.

* Handle unknown exception on authorization check

* fix test:init AuthorizationManager on Auth-enable and set status-500 on topic-lookup-internal-failire

* fail partitionMetadata on zk-failure

* close http-connection on internal server error from broker

* broker kills current session on internal-server-error

* add broker-address into response for client-debugging

* Fix for Infinite loop in PersistentReplicator.startProducer()

* Fix for Infinite loop in PersistentReplicator.startProducer()

On batch-msg dispatching: broker should disconnect consumer which doesn't support batch-message  (#215)

* On batch-msg dispatching: broker should disconnect consumer which doesn't support batch-message

* Close consumer at broker-side without closing connection if consumer doesn't support batch-message

* Fail unsupportedBatchVersion-subscriber if topic has served batch-message

Avoid triggering startReplProducer on newAddProducer as it may flips replicator state wrongly (#232)

* Avoid triggering startReplProducer on newAddProducer as it may flips replicator state wrongly

* Signal replicator is stopping if porducer is not created yet

* read repl-cluster from policies to avoid restart of closing-replicator

* Fix #199: Do not stop to replicate when producer throws exception

* Fix log messages

* testReplicatorProducerClosing shoud be executed at last since it closes pulsar2/pulsar3

* Add unit test for replication resumption on backlog exceeded

Replaced some usages of AtomicInteger, AtomicLong and AtomicReference
for their Atomic*FieldUpdater counterpart on classes which get
instantiated a lot, this should reduce memory usage for the broker
and clients which use lots of topics and consumers.

* Derive direct memory used count from netty counter

* Fix: avoid initial direct-memory assertion with 0

* Generalize PulsarConfigurationLoader

* fix: PulsarConfigurationLoader Test

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