private void addAttribute(Resource.Builder resourceBuilder, String key, String value) {
        final KeyValue.Builder kv = KeyValue.newBuilder()
            .setKey(key)
            .setValue(AnyValue.newBuilder().setStringValue(value));
        resourceBuilder.addAttributes(kv);
    }
Domain of the active provider i.e. specifies prefix to the metrics.

@return Domain in string format.
clients/src/main/java/org/apache/kafka/common/telemetry/internals/ClientTelemetryProvider.java