private static Object2ObjectMap<String, String> getMap(RequestContext ctx) {
        final Object2ObjectMap<String, String> map = ctx.ownAttr(MAP);
        return firstNonNull(map, Object2ObjectMaps.emptyMap());
    }
Unbinds all request-scoped {@link MDC} properties from the specified {@link RequestContext}.

@param ctx the {@link RequestContext}
core/src/main/java/com/linecorp/armeria/common/logging/RequestScopedMdc.java