Symptoms

Applications are unaware of the new or updated aliases after an incremental sync, and only catch up after a full sync.

Steps to reproduce

Setup a directory with aliasing enabled, an create a user ("user") in it.
Connect a client application to the directory.
Synchronise the directory from the client application. The "user" account is propagated to the client application.
In Crowd, create a new alias, e.g., "alias", for "user".
Do an incremental synchronisation from the client application.

The application does not have a "user" account anymore, and instead, it has an "alias" account.

The application still sees "user", and does not have "alias".

incorporates

CWD-3048 Crowd's alias creates multiple accounts

is related to

CWD-2179 When removing a user then their alias names are not removed from database

relates to

CWD-3917 Application syncs from Crowd fail due to "com.atlassian.crowd.model.event.AliasEvent" incorrectly invoked

Testing discovered

CWD-3228 Incremental sync still translates alias for a lowercase-output application after disabling alias support