getType(): DraftEntityType {
    return this.get('type');
  }
An instance of a document entity, consisting of a `type` and relevant
`data`, metadata about the entity.

For instance, a "link" entity might provide a URI, and a "mention"
entity might provide the mentioned user's ID. These pieces of data
may be used when rendering the entity as part of a ContentBlock DOM
representation. For a link, the data would be used as an href for
the rendered anchor. For a mention, the ID could be used to retrieve
a hovercard.