src/vs/workbench/services/themes/common/colorThemeData.ts/ColorThemeData/getColor
class ColorThemeData:	public getColor(colorId: ColorIdentifier, useDefault?: boolean): Color | undefined {
		let color: Color | undefined = this.customColorMap[colorId];
		if (color) {
			return color;
		}
		color = this.colorMap[colorId];
		if (useDefault !== false && types.isUndefined(color)) {
			color = this.getDefault(colorId);
		}
		return color;
	}