protected InternalCacheForClientAccess getCache() {
    InternalCacheForClientAccess cache = cacheProvider.getCache();
    Assert.state(cache != null, "The Gemfire Cache reference was not properly initialized");
    return cache;
  }
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