code: protected Boolean checkHandshake() {
  		if (this.sentHandshake == null) {
  			log.debug("Sent handshake is null, not checking.");
  			return null;
  		}
  		if (this.receivedHandshake == null) {
  			log.debug("Received handshake is null, not checking.");
  			return null;
  		}
  
  		if (!this.sentHandshake.equals(this.receivedHandshake)) {
  			log.error(
  					"Handshakes do not match.  Closing connection to aggregator at {}.",
  					this.session.getRemoteAddress());
  			boolean prevValue = this.stayConnected;
  			this.stayConnected = false;
  			this._disconnect();
  			this.stayConnected = prevValue;
  			return Boolean.FALSE;
  		}
  		return Boolean.TRUE;
  	}
docs: Validates the sent and received handshakes. If either is missing,
  {@code null} is returned. If either is invalid, {@code Boolean.FALSE} is
  returned. If both are valid, {@code Boolean.TRUE} is returned.
  
  @return {@code Boolean.TRUE} if both handshakes (sent/received) are
  valid, {@code Boolean.FALSE} if either is invalid, and
  {@code null} if either is missing.