in log4j2-ecs-layout/src/main/java/co/elastic/logging/log4j2/EcsLayout.java [207:237]
private void serializeTags(LogEvent event, StringBuilder builder) {
ThreadContext.ContextStack stack = event.getContextStack();
List<String> contextStack;
if (stack == null) {
contextStack = Collections.emptyList();
} else {
contextStack = stack.asList();
}
Marker marker = event.getMarker();
boolean hasTags = !contextStack.isEmpty() || (includeMarkers && marker != null);
if (hasTags) {
EcsJsonSerializer.serializeTagStart(builder);
}
if (!contextStack.isEmpty()) {
final int len = contextStack.size();
for (int i = 0; i < len; i++) {
builder.append('\"');
JsonUtils.quoteAsString(contextStack.get(i), builder);
builder.append("\",");
}
}
if (includeMarkers && marker != null) {
serializeMarker(builder, marker);
}
if (hasTags) {
EcsJsonSerializer.serializeTagEnd(builder);
}
}