core/play/src/main/java/play/i18n/Langs.java
public Lang preferred(Collection<Lang> candidates) {
    return new Lang(
        langs.preferred((scala.collection.immutable.Seq) Scala.asScala(candidates).toSeq()));
  }
public Lang preferred(Collection<Lang> candidates) {
    return new Lang(
        langs.preferred((scala.collection.immutable.Seq) Scala.asScala(candidates).toSeq()));
  }
Select a preferred language, given the list of candidates.

<p>Will select the preferred language, based on what languages are available, or return the
default language if none of the candidates are available.

@param candidates The candidate languages
@return The preferred language