code: public void resumeZooKeeper() throws Exception {
          val zk = new ZooKeeperServiceRunner(this.zkPort, this.secureZK, this.tLSKeyStore, this.tLSKeyStorePasswordPath, this.tlsTrustStore);
          if (this.zkServer.compareAndSet(null, zk)) {
              // Initialize ZK runner (since nobody else did it for us).
              zk.initialize();
              log.info("ZooKeeper initialized.");
          } else {
              zk.close();
          }
  
          // Start or resume ZK.
          this.zkServer.get().start();
          log.info("ZooKeeper resumed.");
      }
docs: Resumes ZooKeeper (if it had previously been suspended).
  
  @throws Exception If an exception got thrown.