protected Object[] getKeys(final String regionNamePath, Object[] keys) {
    return (!(keys == null || keys.length == 0) ? keys
        : getRegion(regionNamePath).keySet().toArray());
  }
AbstractBaseController class contains common functionalities required for other controllers.

@since GemFire 8.0
geode-web-api/src/main/java/org/apache/geode/rest/internal/web/controllers/AbstractBaseController.java