[Improvement] Add PMD source code analyser

### What would you like to be improved?

Add and confugure PMD source code analyser (https://pmd.github.io) in our build file.

### How should we improve?

Add PMD to improve code quality and catch some common Java issues.

Locate the repository's build file and review how Java quality checks are configured, then read PMD's integration guidance at https://pmd.github.io. Add and configure PMD so the build runs its analysis and reports common Java issues; done means the build completes with the agreed PMD configuration.

Written by the indexing model from the issue text.