leftJoin

fun <K, inV, otherK, otherV, outV> KStream<K, inV>.leftJoin(    name: String,     globalTable: GlobalKTable<otherK, otherV>,     keySelector: KeyValueMapper<K, inV, otherK?>,     valueJoiner: ValueJoinerWithKey<K, inV, otherV?, outV>): KStream<K, outV>

See also