Runtime error with "GWT 2.4 - expenses sample" - gwt

Question

I am using Eclipse Indigo for Java EE (and I have installed the m2e plugin).
I have a runtime error when launching the "expense" sample given with GWT 2.4. I launch it, the app load, then draw the interface and after the console give this error :
Logging to JettyLogger(null) via com.google.apphosting.utils.jetty.JettyLogger
Successfully processed D:\DL\000-code2012\0-ALL-SRC\6-Expenses\src\main\webapp\WEB-INF/appengine-web.xml
Successfully processed D:\DL\000-code2012\0-ALL-SRC\6-Expenses\src\main\webapp\WEB-INF/web.xml
The server is running at http://localhost:8888/
log4j:WARN No appenders could be found for logger (org.hibernate.validator.util.Version).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.
Sat May 05 12:03:40 BOT 2012 com.google.gwt.sample.expenses.client.ExpensesShell
SEVERE: One or more exceptions caught, see full set in UmbrellaException#getCauses
com.google.web.bindery.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses
at com.google.web.bindery.requestfactory.shared.impl.AbstractRequestContext$StandardPayloadDialect.processPayload(AbstractRequestContext.java:299)
at com.google.web.bindery.requestfactory.shared.impl.AbstractRequestContext$4.onTransportSuccess(AbstractRequestContext.java:951)
at com.google.web.bindery.requestfactory.gwt.client.DefaultRequestTransport$1.onResponseReceived(DefaultRequestTransport.java:136)
etc......
Firstly, to compile successfully the projet I had to quick fix 2 errors in the POM.xml (it was impossible to download files from 2 repositories...so I had to ignore them).
Then, if it is because I have not the "buildhelper" plugin for maven, I just can not found it (I tried it with Maven > Discovery > Catalog)...
I also configured correctly (I suppose) the java compiler for the annotation processing.
Finally, when I clean or compile the project I have a this error (A problem occured) :
Cannot run program "C:\glassfish3\jdk7\bin\javaw.exe" (in directory "D:\DL\000-code2012\0-ALL-SRC\6-Expenses"): CreateProcess error=206, filename or extension too long
Cannot run program "C:\glassfish3\jdk7\bin\javaw.exe" (in directory "D:\DL\000-code2012\0-ALL-SRC\6-Expenses"): CreateProcess error=206, filename or extension too long
It is written twice when I click on "Details"
Could somebody has a solution for this problem ?
Thank you.