fun <T> withLoggingFields(contextMap: Map<String, Any?>?, block: () -> T): T {
 val oldContextMap: Map<String, String>? = MDC.getCopyOfContextMap()
 MDC.setContextMap((oldContextMap ?: mapOf()) + (contextMap?.mapValues { it.value.toString() } ?: mapOf()))
 return try {
  block()
 } finally {
  if (oldContextMap != null) MDC.setContextMap(oldContextMap) else MDC.clear()
 }
}

suspend inline fun <T> withLoggingFieldsSuspend(
	contextMap: Map<String, Any?>?,
	crossinline block: suspend CoroutineScope.() -> T
): T = withContext(
	MDCContext((MDC.getCopyOfContextMap() ?: mapOf()) + (contextMap?.mapValues { it.value.toString() } ?: mapOf()))
) { block() }

Note that you cannot update MDC context from inside of the coroutine simply using MDC.put. These updates are going to be lost on the next suspension and reinstalled to the MDC context that was captured or explicitly specified in contextMap when this object was created on the next resumption. Use withContext(MDCContext()) { ... } to capture updated map of MDC keys and values for the specified block of code.