Runtime exception upon jetty restart on load

[Francesco Malvezzi]

>> Having said that, we know it was a Spring reflection bug and it's long 
>> fixed. I have not seen the issue since, and I have no idea how 
>> somebody would encounter it now. We have a canary unit test in place 
>> so that we'd know if Spring had the issue ever again, and they don't.

In my local IdP there was a jar for a c14n flow having as dependencies 
spring 5.2.4.

I rebuilded the jar with newer spring version (5.3.25) and I would call 
the issue solved.

Not sure if outdated groovy jar also played a role (maybe no) but just a 
confirm the this issue, at least in my case, arises from packages 
imported into shibboleth-idp by users themselves,

thank you again for your directions,

Francesco