@Override
    protected ResourceBundle doGetBundle(final String basename, final Locale locale) {
        try {
            val bundle = ResourceBundle.getBundle(basename, locale, getBundleClassLoader());
            if (bundle != null && !bundle.keySet().isEmpty()) {
                return bundle;
            }
        } catch (final Exception e) {
            LOGGER.trace(e.getMessage(), e);
        }
        return null;
    }
This is {@link CasThemeResourceBundleMessageSource}.

@author Misagh Moayyed
@since 6.6.0
support/cas-server-support-themes-core/src/main/java/org/apereo/cas/services/web/CasThemeResourceBundleMessageSource.java