MqttDefaultFilePersistence drops qos 0 messages

When messages are persisted offline with MqttDefaultFilePersistence and the client simply reconnects, all qos 0 messages are delivered. But when the client establishes a new connection (for instance the application restarts), only one qos 0 message is delivered and the others are dropped.

MqttDefaulltFilePersistence does create 1 file / qos 0 message as expected. It looks like the problem is that all qos 0 messages have an ID of 0 whereas qos 1 and 2 messages have incrementing IDs.

Locate MqttDefaultFilePersistence and trace how persisted files are read after a new connection, comparing that path with reconnect handling. Reproduce the restart scenario with multiple QoS 0 messages and verify that every persisted message is delivered, not only the one sharing the ID 0 value.

Written by the indexing model from the issue text.