Spawn Eggs can't spawn baby entities with custom data

Spawn Eggs with custom data which can swap adult entities correctly can not spawn their baby variations with the correct custom data.

For example:

/give @p zombie_spawn_egg[entity_data={id:zombie,equipment:{mainhand:{id:acacia_boat}}}] 1

This command will spawn a zombie with an acacia boat, but when it spawn its baby variations, there won’t be anything on its hands.