Default values of fields and default values of defaultable function params of abstract objects are not available when referencing

[MaryamZi]

Description:
$title. Need to figure out how we can support the same.

#18404 disallows fields with default values in abstract objects for the timebeing.

The same cannot be done for functions, since the Listener abstract object's attach method has a defaultable parameter.

[MaryamZi]

This is no longer an issue because inclusion only copies the type and the default values are not part of the type.