I'm using an openapi specification, which configures AWS gateway. I'm also using request validation. It works fine with informative error messages if I print out $context.error.validationErrorString in case of 4xx error messages. (In case of missing request data, It will write out exactly which request data is missing)
In case of using multiple schemas for an endpoint in the openapi spec (with using oneOf), validation also works, but the error message does not contain specific message, just that schema matching was not succesfull [instance failed to match exactly one schema (matched 0 out of 1)
I think the problem is that schema validation happens first, so api gw throws this error first. Is there any possibility to find out what is the exact request validation error in this way, so maybe fore api gw to run also the request validation?
Confirmed with AWS support that this is not possible at the moment.