client.collections.create("Artists",
  c -> c.properties(
    Property.reference("bornIn", "Countries"), // single-target
    Property.reference("hasAwards", "Oscars", "Grammys"))); // multi-target

// Add a property to existing collection
var artists = client.collections.use("Artists");
artists.config.addProperty(Property.reference("featuredIn", "Movies"));

artists.data.insert(
  Map.of("name", "Alex"),
  opt -> opt
    .reference("hasAwards", Reference.collection("Grammys", "grammy-0")) // Explicit collection name (useful for multi-target references)
    .reference("hasAwards", Reference.uuids("grammy-1", "grammy-2")) // UUIDs (Weaviate will search different collections for these objects)
    .reference("hasAwards", Reference.objects(grammy_3, oscar_3))); // Create fully-qualified references (collection + uuid) from WeaviateObjects

artists.data.get("artist-0",
  artist -> artist.returnReferences(
    // Artist's references
    QueryReference.multi("hasAwards", "Oscars",
      oscar -> oscar
        .returnProperties("weight")),
            // Nested references
    QueryReference.multi("hasAwards", "Grammys",
      grammy -> grammy
        .returnReferences(
          QueryReference.single("presentedBy"
            academy -> academy
              // Property of an arbitrarily nested reference
              .returnProperties("description"))
        .returnMetadata(MetadataField.ID))));