public SingleRequestCallerBuilder<T> operationTimeout(long operationTimeout, TimeUnit unit) {
      this.operationTimeoutNs = unit.toNanos(operationTimeout);
      return this;
    }
Factory to create an AsyncRpcRetryCaller.
@since 2.0.0
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncRpcRetryingCallerFactory.java