Class not found : PeopleService / SSO with Google Apps Integration (Pro)


The Google Apps Integration (Pro), version 2.6.1 is not working on our wiki.

When connecting, it processes the login and password of the google account, but when redirecting to XWiki, there is the page :
“Authentification Google Apps”

with this message :

Erreur dans l'exécution de la macro [velocity]. Cause : [Could not initialize class]. Cliquer sur ce message pour voir plus de détails.

The class :
is not found.

And the details (extract of the whole java exception) :

java.lang.NoClassDefFoundError: Could not initialize class
 at$Builder$build$ Source)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(
 at GoogleAppsGroovy.updateUser(Script_765581af138cbaea069885f002925edc.groovy:348)
 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(
 at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(
 at java.base/java.lang.reflect.Method.invoke(
 at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(
 at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(
 at org.apache.velocity.runtime.parser.node.ASTMethod.execute(
 at org.apache.velocity.runtime.parser.node.ASTReference.execute(
 at org.apache.velocity.runtime.parser.node.ASTReference.value(
 at org.apache.velocity.runtime.parser.node.ASTExpression.value(
 at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(
 at org.apache.velocity.runtime.parser.node.SimpleNode.render(
 at org.apache.velocity.Template.merge(
 at org.apache.velocity.Template.merge(
 at org.xwiki.velocity.internal.InternalVelocityEngine.evaluate(

It seems it does not find one lib,…
Suprising ! ???

I have checked the installation of the extension,
and deleted it, and reinstalled it.
Same error.

The dependencies tab shows :

Cette extension dépend de:

XWiki 15.10.7
Tomcat 8.5 (last version 8.5.99)
Java 11 (we’ll move up for XWiki 16…)

Is there a extension dependance missing ?

Where does this error come from ?
How to investigate, or solve this ?

Please, any help…

Could it be that :

Google APIs Client Library for Java1.23.0 (dans le wiki Home) Installé

It is “installed”, and not installed as dependency.
may be the classloader cannot access to it ???