[LOG4J2-2912] No Warning if Lookup is defined twice in different dependencies

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.13.3
• Component/s: Configuration, Lookups
• Assignee: Unassigned
• Reporter: D T
• Created: 19/Aug/20 09:01
• Updated: 19/Aug/20 09:14

Description

A long time ago I defined a Lookup called `event` and used it as a dependency for other projects. Somewhen in the meantime, log4j2 added a event lookup as well.

Now my configured pattern does not work anymore, because it uses the internal lookup instead. However, it does not show a warning that there is already a lookup with that name.

It is even more confusing, that if I add the related Log4j2Plugins.dat directly to my project, it uses my Lookup instead of Log4j2's (no warnings). Thats why I didn't notice it during my tests.

 

I only found out about log4j2's new lookup after adding the `packages` attribute to my log4j2.xml. Only then do I get a warning and then even twice directly:

> 2020-08-19 10:57:12,731 main WARN Plugin [event] is already mapped to class org.apache.logging.log4j.core.lookup.EventLookup, ignoring class my.example.LogEventLookup
> 2020-08-19 10:57:13,450 main WARN Plugin [event] is already mapped to class org.apache.logging.log4j.core.lookup.EventLookup, ignoring class my.example.LogEventLookup