Remove redundant code

[yorlov]

Simply cleanup source code

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. This is simply a reminder of what we are going to look for before merging your code.

• I have read the CONTRIBUTING doc
• I have referenced the Jira issue related to my changes in one or more commit messages
• I have added tests that verify my changes
• Unit tests pass locally with my changes
• I have added documentation as necessary
• No Javadoc warnings were introduced with my changes
• No spotbugs warnings were introduced with my changes
• I have interactively tested my changes

Types of changes

What types of changes does your code introduce? Put an x in the boxes that apply

• Infrastructure change (non-breaking change which updates dependencies or improves infrastructure)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Further comments

If this is a relatively large or complex change, start the discussion by explaining why you chose the solution you did and what alternatives you considered.

[MarkEWaite]

This pull request changes the published API of the git client plugin and will break almost all uses of the git client plugin. Removing fetch, init, showRevision, and MergeCommand.Strategy from the published API will break all users of the plugin.

What is your goal with this change?

Did you run the automated tests that are within the plugin and confirm that your proposed changes did not break the automated tests?

Did you test this change interactively?

[yorlov]

This changes don't break compatibility, because modifier 'public' is redundant for interface methods.

Actually visibility of api methods (bytecode level) don't changed and all checks are passed

Major goal is code cleanup