Polish SecurityJacksonModules

Issue gh-3736
* ClassLoader argument - this is required because we do not want to assume
the ClassLoader that should be used
* Clean up logging - logging is now at debug level because we don't expect
all of the modules are loaded (they are quite possibly off the ClassPath)
* Remove ObjectUtils as it was being used on methods that expect a
Collection or Array with non collection based objects
* Polish Javadoc warnings

core/src/test/java/org/springframework/security/jackson2/AbstractMixinTests.java

@@ -37,7 +37,8 @@ public abstract class AbstractMixinTests {
 	protected ObjectMapper buildObjectMapper() {
 		if (ObjectUtils.isEmpty(mapper)) {
 			mapper = new ObjectMapper();
-			mapper.registerModules(SecurityJacksonModules.getModules());
+			ClassLoader loader = getClass().getClassLoader();
+			mapper.registerModules(SecurityJacksonModules.getModules(loader));
 		}
 		return mapper;
 	}