@Override
		public void apply( float[] hsla ) {
			float amount2 = increase ? amount : -amount;

			if( hslIndex == 0 ) {
				// hue is range 0-360
				hsla[0] = (hsla[0] + amount2) % 360;
				return;
			}

			amount2 = autoInverse && shouldInverse( hsla ) ? -amount2 : amount2;
			hsla[hslIndex] = clamp( relative
				? (hsla[hslIndex] * ((100 + amount2) / 100))
				: (hsla[hslIndex] + amount2) );
		}
Increase or decrease hue, saturation, luminance or alpha of a color in the HSL color space
by an absolute or relative amount.
flatlaf-core/src/main/java/com/formdev/flatlaf/util/ColorFunctions.java