[resteasy] How to show helpful error messages for malformed @QueryParam?

As I understand it, a malformed @QueryParam will return a 404 with no message. For example, localhost:8080/api/v1/users?number_param=123 will respond with 404. Apparently, this is due to the JAX-RS spec: ``` 3.2 Fields and Bean Properties if the field or property is annotated with @MatrixParam, @QueryParam or @PathParam then an implementation MUST generate an instance of NotFoundException (404 status) that wraps the thrown exception and no entity ``` I would like the modify this behavior to: 1. Return a 400 status code, as I believe 404 causes confusion for users (they will think the endpoint doesn't exist) 2. Show a helpful error message, for example "'123' is an invalid input for number_param, expected number" I have read that the way to do this is with the ExceptionMapper<E extends Throwable> interface. Is this true? And if so, which Exception E should I use? Is there something like a QueryParamException? If it matters, I am using RESTEasy with Quarkus. Thanks, Arwin