"Class javax/management/MBeanServer violates loader constraints" about run-jetty-run HOT 5 CLOSED

Here's the rest of the log (posted in a comment because original post was too 
long).

...

Caused by: java.lang.LinkageError: Class javax/management/MBeanServer violates 
loader 
constraints
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:675)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:366)
    at org.mortbay.jetty.webapp.WebAppClassLoader.loadClass(WebAppClassLoader.java:337)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:374)
    at 
com.mchange.v2.c3p0.management.ActiveManagementCoordinator.attemptManageC3P0Regi
stry
(ActiveManagementCoordinator.java:52)
    at 
com.mchange.v2.c3p0.C3P0Registry.attemptRegisterRegistryMBean(C3P0Registry.java:
217)
    at com.mchange.v2.c3p0.C3P0Registry.reregister(C3P0Registry.java:242)
    at 
com.mchange.v2.c3p0.impl.PoolBackedDataSourceBase.<init>(PoolBackedDataSourceBas
e.java:2
28)
    at 
com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.<init>(AbstractPoolBackedD
ataSourc
e.java:62)
    at 
com.mchange.v2.c3p0.ComboPooledDataSource.<init>(ComboPooledDataSource.java:108)
    at 
com.mchange.v2.c3p0.ComboPooledDataSource.<init>(ComboPooledDataSource.java:104)
    at 
org.hbf.core.spring.persistence.module.springtransactions.SpringTransactionedHib
ernateModule
$GuiceComboPooledDataSource.getObject(SpringTransactionedHibernateModule.java:20
4)
    at 
org.springframework.beans.factory.support.FactoryBeanRegistrySupport$1.run(Facto
ryBeanRegist
rySupport.java:121)
    ... 107 more

A closer inspection revealed that the problem is C3P0 trying to expose its 
MBeans, see

  http://jira.atlassian.com/browse/CONF-11854

The problem is resolved if you add -
Dcom.mchange.v2.c3p0.management.ManagementCoordinator=com.mchange.v2.c3p0.manage
ment.NullManag
ementCoordinator to the VM arguments in the Eclipse Debug/Run Configuration for 
the project.

You may also be encountering the problem described in issue 27.  I suggested a 
workaround here:

http://code.google.com/p/run-jetty-run/issues/detail?id=27&can=1#c12

James, thanks a lot for your tip. Indeed,

 -Dorg.mortbay.jetty.webapp.parentLoaderPriority=true

solves the problem, too, and I will go for it.

Merged to Issue #27 .