In a GitHub discussion, it has been shared that the injection of plug-in builder attributes of type array from properties files is not working. But... It actually works! The reason it doesn't work for injecting a field of type EventTemplateAdditionalField is the EventTemplateAdditionalField#type field whose name conflicts with the type keyword property file loader uses to determine the type of an element.
This PR renames EventTemplateAdditionalField#type to format. While this is not a backward compatible change, injection of JSON template layout eventTemplateAdditionalFields has already been broken in release 2.14.0 and the introduced fix has already broken the backward compatibility. See
LOG4J2-2961 for details. Hence, it should be okay.