When a proxy repository gets a file that fails content validation it logs a message like this:
2018-06-29 00:00:23,232-0600 WARN [qtp194194304-13484] *UNKNOWN org.sonatype.nexus.repository.view.handlers.ExceptionHandler - Invalid content: GET /net/jcip/annotations/1.0/annotations-1.0.pom: org.sonatype.nexus.repository.InvalidContentException: Detected content type [text/html], but expected [application/xml, text/xml, application/x-xml]: net/jcip/annotations/1.0/annotations-1.0.pom.xml
Note that it does not say which repository has the problem. This makes it very difficult to track the problem down. A problem which could have been solved in seconds requires enabling http debug logging, and then laboriously scanning the output to determine where the bad content is coming from. This can take a considerable amount of time.
Expected: The log message should clearly log which repository the invalid content was received in.