* In C++ allow messages that compress to <5mb to be sent with batching enabled

* Fixed related test

* [pulsar-broker] redelivery tracker use open hashmap

* fix redel count

* Support '--help' option of Pulsar command-line tools.

* Fix a indentation

* Fix a minor bug

*Motivation*

Fixes #3651

`pulsar-io-debezium` is a normal module but not a connector package.
it was added as a connector package by mistake at #3601. This would
cause failing to load connectors during broker starts up.

*Changes*

- remove nar plugin from `pulsar-io-debezium`
- remove `pulsar-io-debezium` from distribution
- add `pulsar-io-kafka-connect-adaptor` in the website

* allow for graceful shutdown when running functions in kubernetes

* cleaning up

* fix unit tests

* Use default queue size in function producer

* Fixed queue size

* Fixed C++ batch acks tracker to evict message from sendList array

* Fixed formatting

* adding memory padding to memory limits set in kubernetes

* cleaning up

* fix: add retry and wait for kubernetes creation/deletion

* cleaning up

* adding retry logic for cleaning up subscriptions

* adjust number of retries

* correcting namespace

### Motivation

Fixes the Apache RAT check to exclude the auto-generated files from Avro compiler and Avro JSON schema definitions.

### Motivation

Building Python wheels is failing in the updated Docker image for Python 3.4, 3.5 and 3.6. Fixing it here by explicitly including the library defined variables.

### Motivation

Fixed flaky test in `AuthPluginTest.testTlsDetectPulsarSslWithHostNameValidation`. The failure 
was due to the fact that test is creating a producer asynchronously but not waiting for the 
future to be completed. 

* If no clusters are specified, the namespace should by default use current cluster

* Don't apply to v1 local namespaces

* It's better to use the isV2() check instead of isGlobal()

[pulsar-broker] provide option to disable redelivery-tracker to reduce in memory positionImpl footprint and gc improvement (#3584)

* [pulsar-broker] provide option to disable redelivery-tracker to reduce in memory positionImpl footprint and gc improvement

* change config name

[Issue 3458: Tag Pulsar ledgers in order to distinguish from other leggers in the same Bookkeeper cluster (#3525)

Fixes #3458

### Motivation

See #3458 

### Modifications

Add a new LedgerMetadataUtils class which holds the logic for building "metadata" to be attached to 

### Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

* [go client] add SubscriptionInitPos option in ConsumerOptions
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

* add comment for SubscriptionInitPos option
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

Signed-off-by: NVinceShieh <vinceshieh@gmail.com>

* [go client] add validation hostName for ClientOptions
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

* [go client] add validation hostName for ClientOptions
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

* rename ValidationHostName to TLSValidateHostname
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

### Motivation

Provides a builtin MongoDB Connector, in order to ease the storage of JSON formated message in MongoDB. It's a sink connector.


### Modifications

Add a new sub-module in the `pulsar-io`module.

### Verifying this change

This change added tests and can be verified as follows:
* deploy the connector with configuration file containing the following fields:
```
configs:
  mongoUri: mongodb://hostname:port
  database: pulsar
  collection: messages
```
* start a mongodb instance
* send messages in the topic declared when deploying the connector
* check in MongoDB if the messages have been stored in the collection `messages`

* moved all windowing related code into its own submodule.

* added pom

* [cpp-client] add multi topic for consumer #3494
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

* use initial_position instead to multi-topics
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>