public ProgressDialogFeature<P> setMessageMapper(final Function<P, String> messageMapper) {
        if (messageMapper != null) {
            this.messageMapper = messageMapper;
        }
        return this;
    }
Feature to surround execution of a worker task visually with a progress dialog
main/src/main/java/cgeo/geocaching/utils/workertask/ProgressDialogFeature.java