GUACAMOLE-926: Clean up unneeded code, trailing whitespace; fix bugs, styling, comments and licenses.

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/base/JDBCDirectory.java

@@ -32,6 +32,7 @@ import org.mybatis.guice.transactional.Transactional;
 public abstract class JDBCDirectory<ObjectType extends Identifiable>
         extends RestrictedObject implements Directory<ObjectType>  {
 
+    @Override
     @Transactional
     public void tryAtomically(AtomicDirectoryOperation<ObjectType> operation)
             throws GuacamoleException {