Currently functions do not report the default Prometheus metrics
like the broker does, or any JMX metrics that normally get
reported by kafka clients.

This add the default Prometheus exports used by the broker as
well as JMX exports that are reported by kafka clients when
using the kafka wrapper.

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

*Motivation*

Bump the development version to 2.6.0-SNAPSHOT

Updated jackson libraries to the latest version. There is a security vulnerability in `jackson-databind` currently used by Pulsar.
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-17531

Motivation
Support messages batch receiving, some application scenarios can be made simpler. Users often increase application throughput through batch operations. For example, batch insert or update database.

At present, we provide the ability to receive a single message. If users want to take advantage of batch operating advantages, need to implement a message collector him self. So this proposal aims to provide a universal interface and mechanism for batch receiving messages.

For example:
```
Messages messages = consumer.batchReceive();
insertToDB(messages);
consumer.acknowledge(messages);
Verifying this change
Added new UT to verify this change.
```

* support mongodb connector

* add tester

* add tester

* add tester

* add  license header

* fix by some comments

* add jdbc source sink

* add init data

* fix code style and default port 27017 of mongodb

* Upgrade bk version to 4.10.0
Signed-off-by: Nxiaolong.ran <ranxiaolong716@gmail.com>

* Handle NoSuchLedgerExistsOnMetadataServer error

* Remove old Pulsar website

* Remove `site/` reference

* Upgrade dependencies for security fixes

* Use guava 18 for jclouds-shaded

* Fix the guava version for HDFS tiered storage component

* Rollback guava to 25.1 since there are API breaking changes

* Rollback to Maven 3.0.5 which has the fix for sec issue

* Fixed Jetty SslContextFactory creation

* Roll back to 9.4.20.v20190813

* Expose metrics of Caffeine and Guava caches

* Fixed test

* removed guava cache instrumentation

* Fixed test

* Removed managed-ledger-shaded artifact

* Fixed dep artifact renaming error

In the official download address of the connector, the connector of Flume, Solr and Redis was not generated correctly.

### Modifications
* Add configuration to io.xml for generate connectors

* Use classloading to load use code for functions

Upgrading to Mockito 2.28 and PowerMock 2.0. This a pre-step to be able to run CI with Java 11 / 12

Fixes #3216 
Implementation of offload to HDFS

### Motivation
Implementation of offload to HDFS

### Verifying this change
Add the test for this

Exclude go module configs check in apache-rat.

### Motivation
- debezium-postgres connector is missing in distribution (build)

### Modifications
- assemby updated

* fix localrun and add tests

* minor fix

* Improving localrun for functions

* improving impl and adding tests

* add missing modules

Fixes #4456

### Motivation
sometimes, user may use sasl client directly, e.g. use cli command bin/pulsar-client, and if sasl-client not included in, it may meet error of `class not found`

* Use same activation dependency in pulsar-client-admin and pulsar-client

* Broker now resolve to same activation dependency as client

* Remove no-longer used activation entries from distribution license

* exclude conflicting activation dependency and update license

* com.sun.activation as only activation dependency in all pulsar modules

* Removed activation-1.1.1.jar reference from presto LICENSE

* [schema] Fix joda dependency issue.

* [schema] Add binary license of joda-time.

* [schema] Make joda-time dependency optional.

* [schema] Change log level to debug for logical type init.

* [schema] fix joda-time license in presto distribution

* [schema] fix joda-time license in presto distribution

* Update bookkeeper ver to 4.9.1

* Update license files

*Motivation*

Currently all the distribution packages are very large. We should provide a way to skip uploading distribution packages.

* Upgrade jackson version to 2.9.8

* Upgrade commons-collections version to 1.10

currently we explored too much internal config for debezium connector, this PR is to hide some details and make the config easier.
expected pass integration tests.

*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

*Motivation*

This change was part of #2714. Moving it out as a separate change to make reviews easier.

*Changes*

Bump bookkeeper version to 4.9.0

*Motivation*

Currently bookie http server is disabled by default. Setting the http server port
to 8000 and include a vertx http server implementation to prepare enabling http server
on bookie.

*Modifications*

Currently bookkeeper only provides two http server bindings, one is vertx, the other one
is finagle server binding. both are netty based http server. so technically it doesn't
introduce additional dependencies. However if people prefers a jetty implementation,
I can add a jetty binding in bookkeeper.

* Upgrade AsyncHTTP client to 2.7.0

* Fixed license files

Supporting the ability to write data to HBase sink #3290