Logging ConditionEvaluationReportMessage object into JsonLayout fails about spring-boot

[wilkinsona]

We could, perhaps, change the code that's logging the message to turn it into a String first. However, there's an outside change that could break someone's existing logging setup that's relying up it being logged as an object for some reason.

Alternatively, you may be able to get this to work by customising the ObjectMapper that Log4j2 is using with a custom serializer for the ConditionEvaluationReportMessage. That converter could be as simple as calling toString() on it.

[Armstrong4444]

Unfortunately, I couldn't find any way to customize the ObjectMapper that log4j2 is using. The ObjectMapper is instantiated in https://github.com/apache/logging-log4j2/blob/rel/2.21.1/log4j-core/src/main/java/org/apache/logging/log4j/core/layout/JacksonFactory.java#L88. This ObjectMapper object is used here: https://github.com/apache/logging-log4j2/blob/e613e9ed71279bb52753a4df810d61c11389df81/log4j-core/src/main/java/org/apache/logging/log4j/core/layout/JacksonFactory.java#L276. The ObjectWriter, which is created from the ObjectMapper, probably can't be customized either, as it is wrapped in JsonLayout without any accessor.

Just one way I see to solve this within Log4j2 is to create a completely new customized JsonLayout (for example MyJsonLayout) plugin instead of using the standard Log4j2 JsonLayout plugin. However, I probably wouldn't do that and would come to accept this issue for the time being.