[Java - Beam Schema] Manually Generating a Beam Schema for a POJO class

[Kaymak, Tobias]

I have the following class definition:

public class EnrichedArticle implements Serializable {

  // ArticleEnvelope is generated via Protobuf
  private ArticleProto.ArticleEnvelope article;
  // Asset is a Java POJO
  private List<Asset> assets;

  public EnrichedArticle(ArticleProto.ArticleEnvelope article, List<Asset>
assets) {
    this.article = article;
    this.assets = assets;
  }
}

I am trying to generate a SerializableFunction<EnrichedArticle, Row> and a
Schema for it so that I can pass it easily to my BigQueryIO at the end of
my pipeline. Transforming the article to a Row object is straightforward:

First I get the toRow() function for it via the helper:

 new ProtoMessageSchema().toRowFunction(TypeDescriptor.of(
      ArticleProto.ArticleEnvelope.class));

Then I just apply that function to the article field.
However I don't know how I can manually transform my list of assets (a
simple Java POJO annotated with: @DefaultSchema(JavaFieldSchema.class)

in my EnrichedArticle container/composition class. What's the recommended
way of doing this?