Models - snappify.com

VideoBlock.java

@AutoValue
public abstract class VideoBlock implements Block {
  @SerializedName("source")
  public abstract String source();

  @SerializedName("thumbnail")
  public abstract String thumbnail();

  @SerializedName("title")
  public abstract String title();

  @SerializedName("duration")
  public abstract int duration();
}

ImageBlock.java

@AutoValue
public abstract class ImageBlock implements Block {
  @SerializedName("source")
  public abstract String source();

  @Nullable
  @SerializedName("author")
  public abstract String author();

  @Nullable
  @SerializedName("description")
  public abstract String description();
}

Block.java

public interface Block {
}

TextBlock.java

@AutoValue
public abstract class TextBlock implements Block {
  @SerializedName("text")
  public abstract String text();
}