Book.java

@Getter
@Setter
@RequiredArgsConstructor
@AllArgsConstructor
@Builder
@Document(indexName = "book")
public class Book {

    @Id
    private String id;

    @MultiField(mainField = @Field(type = Text, fielddata = true), otherFields = { @InnerField(suffix = "verbatim", type = Keyword) })
    private String title;

    @Field(type = Nested, includeInParent = true)
    private Author author;

    @Field(type = Keyword)
    private String[] tags;
}