fix gc issue

Author: jaydeluca

instrumentation/internal/internal-class-loader/javaagent-integration-tests/src/test/java/io/opentelemetry/javaagent/instrumentation/internal/classloader/ResourceInjectionTest.java

@@ -42,6 +42,7 @@ void resourcesInjectedToNonDelegatingClassLoader() throws Exception {
 
     Enumeration<URL> resourceUrls = emptyLoader.get().getResources(resourceName);
     assertThat(resourceUrls.hasMoreElements()).isFalse();
+    resourceUrls = null;
 
     URLClassLoader notInjectedLoader = new URLClassLoader(urls, null);