Fix "argument type mismatch" on link save

[ruthst00]

Fixes #2172

Root Cause & Fix (AnnotatedEventHandlerInvoker.java)

In onApplicationEvent(), when processing a LinkedEntityEvent, the code correctly filtered handlers by the source/parent type but blindly passed the linked object to all matching handlers — even those whose second parameter expected a different linked-entity type. The fix adds a type-compatibility check: if the handler method has a second parameter and the linked object's type is not assignable to it, the handler is skipped via continue.

Test (AnnotatedEventHandlerInvokerUnitTests.java)

Added invokesOnlyMatchingLinkedEntityTypeHandlerForLinkSaveEvent() (tagged GH-2172) which registers a MultiLinkedEntityHandler with two @HandleBeforeLinkSave methods — one for TaskStatus and one for TaskCategory — and verifies that firing a BeforeLinkSaveEvent with each linked type invokes only the correct handler without throwing an exception.

The commit (16382620) includes Signed-off-by: ruthes00 <ruthes00@gmail.com> and @author Steve Rutherford in both changed file headers.

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