Allow structure logging "name already written" errors caused by MDC to be logged as warnings

[philwebb]

As discussed in #45063, currently an MDC name that has already been used will throw an IllegalStateException and prevent that message from being logged at all. It would be better if we allowed the structured logging to continue without the offending element and issued a warning instead.

[wolframhaussig]

I am currently running into this issue, because I am using the Elastic APM Java Agent, and it adds the error.id to the MDC:
https://www.elastic.co/docs/reference/apm/agents/java/logs#log-correlation-ids

[pauldburton]

I am currently running into this issue, because I am using the Elastic APM Java Agent, and it adds the error.id to the MDC: https://www.elastic.co/docs/reference/apm/agents/java/logs#log-correlation-ids

@wolframhaussig have you figured out any way around this? We are in the same boat.

[wolframhaussig]

I am currently running into this issue, because I am using the Elastic APM Java Agent, and it adds the error.id to the MDC: https://www.elastic.co/docs/reference/apm/agents/java/logs#log-correlation-ids

@wolframhaussig have you figured out any way around this? We are in the same boat.

Unfortunately not. Currently, we do not use the structured logging in our production versions....

[snicoll]

There is a similar ask with a different context to consider when looking at this, see #47645.

[jnewald]

We do use structured logging and found a workaround just by setting the property logging.structured.json.context.prefix. So the error.id coming from elastic (and all other current mdc entries) gets wrapped in a sub-element named by this prefix.

Unfortunately this property is sparely documented but it works.

[michbeck100]

Also ran into this issue. Would be great to log this only as warning. Currently i cannot reproduce the error locally so it would be good to see the generated json log to pinpoint the problem.
Maybe the duplicate name could be suffixed with a number? So you can see both values.