Use class names for selectors to avoid locking in classloader

Fixes #2257

Use the class name in the selector, rather than a class object, to avoid 'locking in' the classloader of the class. Locking in the class prevents thread context classloaders being used in the discovery phase to load classes.

Author: holly-cummins

org.eclipse.jdt.junit5.runtime/src/org/eclipse/jdt/internal/junit5/runner/JUnit5TestLoader.java

@@ -75,7 +75,7 @@ private ITestReference createFilteredTest(Class<?> clazz, String testName, Strin
 	}
 
 	private ITestReference createUnfilteredTest(Class<?> clazz, String[][] includeExcludeTags, String[] failureNames) {
-		LauncherDiscoveryRequestBuilder requestBuilder= LauncherDiscoveryRequestBuilder.request().selectors(DiscoverySelectors.selectClass(clazz)).filters(getTagFilters(includeExcludeTags));
+		LauncherDiscoveryRequestBuilder requestBuilder= LauncherDiscoveryRequestBuilder.request().selectors(DiscoverySelectors.selectClass(clazz.getName())).filters(getTagFilters(includeExcludeTags));
 		if (failureNames != null && failureNames.length > 0) {
 			String failureNamesString= ""; //$NON-NLS-1$
 			for (String failureName : failureNames) {