maven does not load referenced libraries in Eclipse

 The project in Eclipse reports Unbound classpath variable: 'M2_REPO/**/***/***.jar'

But in fact this jar exists in the MAVEN directory on my local machine:

C:\Documents and Settings\kaseyxiong\.m2\repository\**\***\***.jar

It means that the parameter M2_REPO is not recognized by Eclipse, so it needs to be added:

Eclipse->Windows->Preferences->java->Build Path->Classpath Variables

New one, the name is M2_REPO , do not change the name, select folder for the attribute, point to C:\Documents and Settings\xx\.m2\repository