open fun putIfAbsent(: K, : V, : Handler<AsyncResult<V>>): Unit
Put the entry only if there is no entry with the key already present. If key already present then the existing value will be returned to the handler, otherwise null.
completionHandler - the handler
open fun putIfAbsent(: K, : V, : Long, : Handler<AsyncResult<V>>): Unit
Link io.vertx.reactivex.core.shareddata.AsyncMap#putIfAbsent but specifying a time to live for the entry. Entry will expire and get evicted after the ttl.