### Motivation

Most of the configuration classes of the connectors had the following annotations:

```
@data
@Setter	
@Getter	
@EqualsAndHashCode	
@ToString
```

The [@data](https://projectlombok.org/features/Data) annotation includes all other annotations:

> All together now: A shortcut for @ToString, @EqualsAndHashCode, @Getter on all fields, @Setter on all non-final fields, and @RequiredArgsConstructor!


### Modifications

Removed `@Setter`, `@Getter`, `@EqualsAndHashCode`, and '@ToString' if the `@data` annotation was also present

Fixes #5612 


### Motivation
for MongoSink 

### Modifications
 replace ”com.mongodb.async.client” package with ”com.mongodb.reactivestreams.client.”

*Motivation*

Bump the development version to 2.6.0-SNAPSHOT

Use StandardCharsets.UTF_8 for converting String to bytes to avoid potential encoding error.

* Add a source connector for MongoDB

* Fix expected license header

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

### Motivation

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

### 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`