Why does the color of the icon change when I set an icon on a button?

Question

Java

When the button is set to enable, and the icon is displayed on it, the color of the icon changes (its color is black and it is displayed as gray), I assume that the colors overlap each other, but is it possible to disable this somehow?
This is a screenshot of the code where the color and icons on the buttons are set.

Link to gitHub if someone is interested and not too lazy to open it.
https://github.com/AlexandrPonomarenko