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Support plugin for MongoDB

Response for "Add checkstyle", close #149 

fix collector cannot start issue

Add “checkStyle.xml” and “codeStyle.xml” files, varify the code-style when “mvn compile” and CI. This is the initialized commit.

fix start error issue

Going to adjust some comments after merge.

* add comments class in selector package

* actor comments

* 1. comments of collector config
2. index creator support options: overwrite, ignore, off

* fix index testcase bug

* fix comments

* change the config of index creat to index initialize model

* test case failure

update docker image