[USER STORY] Report indentation formatting violations in source code

[jody]

User Story

As a developer, I want indentation violations in source code to be automatically identified and reported, so that the Java coding convention regarding indentation is maintained.

Acceptance Criteria

Given the source code for the project,
When the ant checkstyle task is run,
Then the source code is checked for standard indentation, using the Java basic offset of 4 spaces, and any violations are shown in the associated checkstyle report.

Notes

Consider adding the following lines to lib/jp_checks.xml

        <!-- Indentation Checks.                                                -->
        <!-- See https://checkstyle.sourceforge.io/checks/misc/indentation.html -->
        <module name="Indentation"/>

These would need to appear within the treewalker module.