This looks just like another example of hostile downvoting which I was trying to fight formerly here. I have no problems with cases where downvotes are accompanied by nothing but a close vote, since this could replace a comment to some degree. But leaving just a downvote (like done here) is clearly not constructive, since it does not show any indication of what the asker might have done wrong. I don't expect any of the downvoters here to show up on meta to explain themselves, they seem to prefer hiding in their anonymity.
That said, I think the question in stake is not really a good question as it is written, since it seems to present a working solution, and gives me the impression of asking for a discussion or general feedback for it (not literally, but that is not the point). However, the SE sites are not discussion sites, and the community here on SE.SE prefers questions with real issues, not just vague non-issues.
If, for example, the question would look like
I tried out to standardize the handler signatures in the following way, but this leads to issues X and Y
and then asking about a solution for X and Y, that might be something way more answerable. And it would show your efforts to test your design first by yourself before asking others, which is currently not apparent.
Another problem I see with the question, it is actually hard to understand without the example behind the external link. Such external sources tend to have a life time shorter than a question on SE, so better take the time, put the relevant code snippet into the question, and remove the link to the external code sample.
Let me add, in between the question got also 3 upvotes, maybe counter-upvotes, since fortunately there seem to be enough people here in the community who disagree with those hostile downvoters and try to balance their behaviour.