Add flags to PREPARE message in protocol v5

Description

adds a flags field to the PREPARE message.
The server-side ticket will be merged soon. We don't need to implement 1350 immediately, but the protocol will break if the flags are not present.

Add a blank flags field to preserve compatibility.

Environment

None

Pull Requests

None
Fixed

Assignee

Unassigned

Reporter

Olivier Michallat

Labels

None

PM Priority

None

Affects versions

None

Fix versions

Pull Request

None

Doc Impact

None

Size

None

External issue ID

None

External issue ID

None

Sprint

Java 4.x

Priority

Minor
Configure