src/vs/workbench/services/themes/common/colorThemeData.ts/ColorThemeData/overwriteCustomColors
class ColorThemeData:	private overwriteCustomColors(colors: IColorCustomizations) {
		for (let id in colors) {
			let colorVal = colors[id];
			if (typeof colorVal === 'string') {
				this.customColorMap[id] = Color.fromHex(colorVal);
			}
		}
	}