When NiFi is restarted, if FlowFile is queued for a connection that no longer exists, the FlowFile remains but its data does not

When NiFi is restarted, if there is data in the FlowFile Repository that maps to a given connection, it is placed back into the queue for that connection. If the connection does not exist, it logs a WARNING like the following:

nifi-app_2020-08-04_12.0.log:2020-08-04 12:18:19,840 WARN [main] o.a.n.c.r.WriteAheadFlowFileRepository Encountered Repository Record (id=137) with Queue identifier ba3261a3-0173-1000-4582-5ee7cffe1e8b but no Queue exists with that ID. Dropping this FlowFile

The data is not actually dropped - it remains within the NiFi instance and if the flow is restored to have the connection and NiFi is restarted, the FlowFile will be placed back into the queue. However, when the connection does not exist, the Claimant Count is not incremented for the Content Claim. As a result, the data may be reclaimed by the Content Repository. As a result, when the flow is restored and NiFi restarted, the data exists in the queue but its content is gone.