src/vs/editor/browser/viewParts/minimap/minimap.ts/MinimapOptions/_getMinimapForegroundOpacity
class MinimapOptions:	private static _getMinimapForegroundOpacity(theme: EditorTheme): number {
		const themeColor = theme.getColor(minimapForegroundOpacity);
		if (themeColor) {
			return RGBA8._clamp(Math.round(255 * themeColor.rgba.a));
		}
		return 255;
	}