code: public static TimestampBound ofReadTimestamp(Timestamp timestamp) {
      return new TimestampBound(Mode.READ_TIMESTAMP, checkNotNull(timestamp), null);
    }
docs: Returns a timestamp bound that will perform reads and queries at the given timestamp. Unlike
  other modes, reads at a specific timestamp are repeatable; the same read at the same timestamp
  always returns the same data. If the timestamp is in the future, the read will block until the
  specified timestamp, modulo the read's deadline.
  
  <p>This mode is useful for large scale consistent reads such as mapreduces, or for coordinating
  many reads against a consistent snapshot of the data.