Error handling for debugging

[kkovarik]

Error handling tweaks

Recently was trying to use plugin on Keycloak (6.x), some minor tweaks that came out of it:

Try catch in ContentTypeHelper

Changed the try cache exception - maybe because of using older version of keycloak? Or some classpath issues, as on my instance there was org.jboss.resteasy.spi.BadRequestException instead of javax.ws.rs.BadRequestException. Changed to general Exception as it really doesn´t matter why recognition failed.

Logging general exception in ValidateEndpoint

Previous error was not easily debugged without it, as the exception was not logged properly. Had another issues with missing jaxb on classpath that needed to be properly logged as well. If something unexpected happens, it should be logged and at least some UUID of error added.

[hanusto]

@Doccrazy can you please do review?