docs: public MongodbQueue<ID, DATA> init() throws Exception {
          if (getMongoClient() == null) {
              setMongoClient(buildMongoClient(), true);
          }
  
          super.init();
  
          if (getMongoClient() == null) {
              throw new IllegalStateException("MongoDB Client is null.");
          }
  
          initCollection();
  
          return this;
      }