This is a spinoff from Erick Erickson's efforts over in SOLR-10778
The goal is a warning-free compilation, followed by enforcement of build failure on warnings, with the idea of suppressing innocuous warnings to the extent that the remaining warnings be treated as build failure.
fix java7 warnings in the source code
Get precommit Lint warnings out of test code
Removed deprecated code in solr/core (master only)
Address precommit WARNINGS
GitHub Pull Request #1563