These changes should have been present in #673

I don't think that this is the right approach. The current approach there is a stop-gap solution which has side-effects as noted in the TODO.

See my alternative proposal in #852

I think that we can close this issue now that #852 has landed. Landing this change is not mutually exclusive, but will lead to further b/c breakages in future when we do release 2.0 and stop converting modifying the content of $this->capabilities.

Do you agree @OndraM?

Sure, closing this, as it has been covered by #852. Thanks @gvlasov for the suggestion, though!