> The remote repo for https://bits.netbeans.org/maven2/ is configured to Generate if absent
For all proxy repos in repo.jenkins-ci.org ensure that none of them have that setting. (ie this is what allows artifactory to download HTML when an artifact is requested and serve it up with a freshly generated checksum to all consumers).
This means that consumers can not use "strict" checking, or things like it. missing checksums muss never be created on the fly - it should be a simple garbage in garbage out proxy.
In other words all proxy rpos should be set to either "Ignore and Pass-thru:" or "Fail".
Fail should be the default - it was agens since a buggy maven pushed some things with broken checksums, and consuming artifacts without a checksum and caching them means you may well get silent corruptions. However if that is too much of a step for the project due to still consuming some ancient artifact, or a awful maven repo then please use "Ignore and Pass-thru".
The latter will allow consumers to block these as they so choose.