While triaging a Spring Boot issue, I've learned that Hibernate Validator fails with an ArrayIndexOutOfBoundsException if a ParameterNameProvider returns fewer names than the Method or Constructor has arguments. While the javadoc doesn't specifically say that the number of names returned should match the number of parameters (or be zero), I think this is a bug in the name provider. However, I wondered if you might want to consider making Hibernate Validator a little more resilient in the face of a misbehaving name provider.