Markers are not included as key-value pairs

I was trying to add a custom Marker to the JSON output of the EcsEncoder in Spring Boot (using Slf4J & Logback) using the following command:

log.info(
        append("my_custom_metric", incidentCount),
        "Collecting incident metrics, # of incidents: {}",
        incidentCount);

Expecting the following JSON output:

{ "message":"Collecting incident metrics, # of incidents: 0", "tags":[{"my_custom_metric": 0}] }

However, I got this non-useful value instead:

{ "message":"Collecting incident metrics, # of incidents: 0", "tags":["LS_APPEND_OBJECT"] }

Checking the source code, the EcsEncoder.java is using just marker.getName(), which in my eyes is the most useless value to use from the Marker. Isn't the whole idea of the markers that you can add your own, custom values to the Json output?
I believe we should be using marker.getFieldName() and marker.getFieldValue() as key value pair in the output, not the name of the marker. Am I missing something?

ecs-logging-java/logback-ecs-encoder/src/main/java/co/elastic/logging/logback/EcsEncoder.java

Lines 159 to 161 in 2526531

    
           private void serializeMarker(StringBuilder builder, Marker marker) { 
        
               if (marker != null) { 
        
                   EcsJsonSerializer.serializeSingleTag(builder, marker.getName());

After thinking about it over the weekend, I realised that it makes sense that something called a "marker" is not more than a single value - as implemented.

However I still do wonder what the use is for the fieldName and fieldValue is when it gets ignored, especially as the official documentation says one should use it like my example.

marker.getFieldName() and marker.getFieldValue() as key value pair in the output, not the name of the marker. Am I missing something?

The thing is that the getFieldName and getFieldValue methods are not part of the org.slf4j.Marker interface but are part of logstash-logback-encoder. But adding support for these markers does sound like a good idea. See also #49

Ah indeed, I was looking at the specific implementations of Marker. I think my question is answered then, and #49 should be sufficient to capture my request.
Thanks!

	private void serializeMarker(StringBuilder builder, Marker marker) {
	if (marker != null) {
	EcsJsonSerializer.serializeSingleTag(builder, marker.getName());