List<MyBookProjection> hits = searchSession.search( Book.class )
        .select( f -> f.composite()
                .from(
                        f.field( "title", String.class ),
                        f.object( "authors" )
                                .from(
                                        f.fromRoot( f.id() ), // We EXPLICITLY tell HSearch to use the root ID
                                        f.field( "authors.firstName", String.class ),
                                        f.field( "authors.lastName", String.class )
                                )
                                .as( MyBookProjection.Author::new )
                                .multi()
                )
                .as( MyBookProjection::new ) )
        .where( f -> f.matchAll() )
        .fetchHits( 20 );