since v10.0.120

The extension point AgentTicketActionValidator is a java interface that can be implemented to validate various actions performed by an agent concerning a ticket.

All required information about the agent and the ticket is provided by the AgentTicketAction parameters, which are passed to the various method calls. If you don't need to distinguish the different actions you can just override the method with the AgentTicketAction parameter. Otherwise override the method(s) that suite your needs.