[JAVA] Fix optional collection initialized with object [fix: #18735] #775

Job	Run time
Build sbt/Scala client, servers (samples/client/petstore/java/okhttp-gson)	41s
Build sbt/Scala client, servers (samples/client/petstore/scalaz)	40s
Build sbt/Scala client, servers (samples/client/petstore/scala-pekko)	41s
Build sbt/Scala client, servers (samples/server/petstore/scala-lagom-server)	6m 6s
Build sbt/Scala client, servers (samples/server/petstore/scala-play-server)	11m 39s
Build sbt/Scala client, servers (samples/server/petstore/scala-akka-http-server)	10m 12s
Build sbt/Scala client, servers (samples/server/petstore/scala-pekko-http-server)	47s
Build sbt/Scala client, servers (samples/server/petstore/scalatra)	3m 1s
Build sbt/Scala client, servers (samples/server/petstore/scala-finch)	4m 43s
Build sbt/Scala client, servers (samples/server/petstore/scala-http4s-server)	45s
Build sbt/Scala client, servers (samples/server/petstore/scala-cask)	1m 11s
	40m 26s

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