ModuleServlet Logger should be "private static final"
In the ModuleServlet class: https://github.com/openmrs/openmrs-core/blob/master/web/src/main/java/org/openmrs/module/web/ModuleServlet.java#L31 private Logger log = LoggerFactory.getLogger(this.getClass()); Should be changed to: private static final Logger log = LoggerFactory.getLogger(ModuleServlet.class); Background information: Loggers should be: private: never be accessible outside of its parent class. If another class needs to log something, it should instantiate its own logger.
static: not be dependent on an instance of a class (an object). When logging something, contextual information can of course be provided in the messages but the logger should be created at class level to prevent creating a logger along with each object.
(final|const): be created once and only once per class.