Add a new connector ' flink-connector-rocketmq'

[mikiaichiyu]

What is the purpose of the change

Added a new flink-connector to connect RocketMQ cluster, then can implement the message producing and consumering with RocketMQ, and also the connector can be used as data souce or data sink to integrate Flink and RocketMQ cluster

Brief change log

• Added the RocketMQ sink and source implementation
• Added some unit test
• Added a pom.xml which includes the specail dependence about RocketMQ client version 3.2.6
• Added a simple README .md

Verifying this change

(Please pick either of the following options)

This change is already covered by existing tests, such as (please describe tests).

the unit test can test some construct functions

Documentation

• Does this pull request introduce a new feature? (yes )
• If yes, how is the feature documented? (docs, in README.md)

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Automated Checks

Last check on commit bc1d3d4 (Fri Aug 23 10:18:53 UTC 2019)

Warnings:

• 2 pom.xml files were touched: Check for build and licensing issues.
• Documentation files were touched, but no .zh.md files: Update Chinese documentation or file Jira ticket.
• Invalid pull request title: No valid Jira ID provided

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Review Progress

• ❓ 1. The [description] looks good.
• ❓ 2. There is [consensus] that the contribution should go into to Flink.
• ❓ 3. Needs [attention] from.
• ❓ 4. The change fits into the overall [architecture].
• ❓ 5. Overall code [quality] is good.

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CI report:

• ae86a13 : FAILURE Build
• 2b6b491 : FAILURE Build
• d294b81 : FAILURE Build
• bc1d3d4 : SUCCESS Build

[mikiaichiyu]

Hi @tillrohrmann

When I try to add a new connector to flink I found I have to get a JIRA ticket first, and I go to https://flink.apache.org/contributing/contribute-code.html -> 'Flink’s bug tracker: Jira.' then I found I can't get the entrance for ticket. since it's the first time to commit to flink I think I need your help, could you please let me know how to get the ticket for the commit? thanks

[tillrohrmann]

Hi @mikiaichiyu, have you seen the existing JIRA issues for adding a RocketMQ connector https://issues.apache.org/jira/browse/FLINK-5726? Before adding a new connector to Flink you should start a dev ML discussion to reach agreement. Once this is done, a committer needs to shepherd the effort and then you can get assigned to FLINK-5726. Only then, you should open a PR because otherwise it is not guaranteed that the PR gets the attention it deserves.