Plugin Help Essentials Source Code

I want someone to help me to edit the essentials source code on spawners so that when players buy spawners using essentials sign, it won't say placing default spawner and give the players a pig spawner again.

Ps: When players buy a zombie spawner using essentials sign, it will give the player a spawner named zombie spawner instead of giving him a spawner named monster spawner. I want to keep usingessentials sign and silk spawners.

Can someone or a developer help me? I'll be very appreciated.

EDIT: @nverdier Maybe you can help me.