It is impossible to avoid the deprecated AggregationBuffer when implementing a GenericUDAFEvaluator

To create a custom UDAF I derived from GenericUDAFEvaluator (in scala). The public interface of this class uses the AggregationBuffer class.
The scala compiler complains because the interface of my class makes heavy use of a deprecated type (AggregationBuffer) - however there is no way to use the suggested AbstractAggregationBuffer due to the interface of the parent class.

Expected behaviour: As long as AggregationBuffer is still an unavoidable part of the public interface it should not be marked deprecated.
If it remains deprecated, GenericUDAFEvaluator methods should take AbstractAggregationBuffer arguments instead.