At the present time, there's no way to get texture data for an OfflinePlayer.

This is problematic when working with player heads, as there's no way to access texture data via the API: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/block/Skull.html 

I believe having this data under OfflinePlayer would make the most sense, as texture data is generally stored under owner information within the block data.

The following is an example of data I'd like to see accessible: 

Thanks!