How can I add a color to leaher clothes

Hello,
Im developing a PaintBall Plugin, and I want to Use the Coloring System for Leather Clothes. But i cant find the API Can you give me a example, please?
My Code:

Code:

PlayerInventory pi = ((Player) sender).getInventory();
 
ItemStack helmet = new ItemStack(Material.LEATHER_HELMET);
 
pi.setHelmet(helmet);

But it needs to be coloured!
Thanks in advance!

- boomer41