比如，用scala原生mongodb-scala-driver時，maven是：

<!--scala-mongodb-->
        <dependency>
            <groupId>org.mongodb.scala</groupId>
            <artifactId>mongo-scala-driver_2.11</artifactId>
            <version>1.0.1</version>
        </dependency>
 

如果mongodb需要認證，在credentialList按ctrl+滑鼠左鍵看的時候是:

public MongoClientSettings.Builder credentialList(List<MongoCredential> credentialList) {
            this.credentialList = Collections.unmodifiableList((List)Assertions.notNull("credentialList", credentialList));
            return this;
        }
 

為JavaList。因此，scalaList需要.asJava轉換成JavaList。
先import scala.collection.JavaConverters._ 才有.asJava方法。
會有：

val settings: MongoClientSettings = MongoClientSettings.builder() .clusterSettings(clusterSettings).credentialList(credentialList.asJava) .sslSettings(SslSettings.builder().enabled(true).build()) .streamFactoryFactory(NettyStreamFactoryFactory()) .build()