code: public Boolean exists(final byte[] key) {
          return this.execute(new RedisClusterCallback<Boolean>() {
              public Boolean doInRedisCluster(RedisCluster redisCluster) {
                  return redisCluster.exists(key);
              }
  
              public int getPartitionNumber() {
                  return GatewayPartitionNumber.get(key);
              }
  
              public AffinityState getState() {
                  return AffinityState.READ;
              }
          });
      }
docs: /*
  @see BinaryRedisClusterCommands#exists(byte[])