How to config the js library when it's shared by multiple customized widgets ?

Hi, 

I have two widgets need to use the same javascript library , I tried to put the library under the folder lib/js and add the following line in metadata.xml for the widget which need the library: 

<FileResource description="" file="../Common/extensions/NSTWidget/lib/js/echarts.js" isDevelopment="false" isRuntime="true" type="JS"/>

But uploading the extension will raise error : "[context: Extension Exception][message: com.thingworx.common.exceptions.InvalidRequestException: Illegal Path - Relative URLs not permitted]" 

How should I reference the js library if it's shared by multiple customized widgets ? 

Regards,

Sean