JDK-8327255 added build.gradle support for enabling javac lint warnings, and then JDK-8334161 added -Werror to treat warnings as errors. We should do the same for tests, once the tests are lint clean.

This would be done by added the list of lint options to the "defaultTestLintOptions" variable in build.gradle. To test this prior to changing build.gradle, run gradle test with the "-PTEST_LINT" option.