...

<apps>
  <app name="my-app" ...>
    <captureTransactionLatencyStats>true</captureTransactionLatencyStats>
    <captureEventLatencyStats>true</captureEventLatencyStats>
    <captureMessageTypeStats>false</captureMessageTypeStats>
  </app>
</apps>

 Per message type latency stats are not currently emitted in heartbeats due to concerns over the size they would contribute to heartbeats. Instead, they can be traced using the aep engine stats thread. 

 See Also: 

• DDL Config Reference for more details about the above stats. 
• AEP Engine Statistics for more detail about app-level stats.

...