private Map<String, Object> getClientCustomProps() {
        final Map<String, Object> props = originals();
        props.keySet().removeAll(CONFIG.names());
        props.keySet().removeAll(ConsumerConfig.configNames());
        props.keySet().removeAll(ProducerConfig.configNames());
        props.keySet().removeAll(AdminClientConfig.configNames());
        props.keySet().removeAll(originalsWithPrefix(CONSUMER_PREFIX, false).keySet());
        props.keySet().removeAll(originalsWithPrefix(PRODUCER_PREFIX, false).keySet());
        props.keySet().removeAll(originalsWithPrefix(ADMIN_CLIENT_PREFIX, false).keySet());
        return props;
    }
Get a map of custom configs by removing from the originals all the Streams, Consumer, Producer, and AdminClient configs.
Prefixed properties are also removed because they are already added by {@link #getClientPropsWithPrefix(String, Set)}.
This allows to set a custom property for a specific client alone if specified using a prefix, or for all
when no prefix is used.

@return a map with the custom properties
streams/src/main/java/org/apache/kafka/streams/StreamsConfig.java