Unable to add Maven 2 project with many email addresses in CI notifier

javax.jdo.JDOUserException: Field org.apache.maven.continuum.model.project.Project.projectGroup is null, but is mandatory as its described in the jdo metadata

javax.jdo.JDOUserException: Field org.apache.maven.continuum.model.project.Project.projectGroup is null, but is mandatory as its described in the jdo metadata
at org.jpox.store.rdbms.fieldmanager.ParameterSetter.storeObjectField(ParameterSetter.java:131)
at org.jpox.state.StateManagerImpl.providedObjectField(StateManagerImpl.java:2771)
at org.apache.maven.continuum.model.project.Project.jdoProvideField(Project.java)
at org.apache.maven.continuum.model.project.Project.jdoProvideFields(Project.java)
at org.jpox.state.StateManagerImpl.provideFields(StateManagerImpl.java:3115)
at org.jpox.store.rdbms.request.UpdateRequest.execute(UpdateRequest.java:259)
at org.jpox.store.rdbms.table.ClassTable.update(ClassTable.java:2573)
at org.jpox.store.StoreManager.update(StoreManager.java:998)
at org.jpox.state.StateManagerImpl.flush(StateManagerImpl.java:4928)
at org.jpox.state.StateManagerImpl.nullifyFields(StateManagerImpl.java:4440)
at org.jpox.AbstractPersistenceManager.preCommit(AbstractPersistenceManager.java:3371)
at org.jpox.store.rdbms.RDBMSNonmanagedTransaction.commit(RDBMSNonmanagedTransaction.java:400)
at org.codehaus.plexus.jdo.PlexusJdoUtils.updateObject(PlexusJdoUtils.java:163)
at org.apache.continuum.dao.AbstractDao.updateObject(AbstractDao.java:93)
at org.apache.continuum.dao.AbstractDao.updateObject(AbstractDao.java:85)
at org.apache.continuum.dao.ProjectGroupDaoImpl.updateProjectGroup(ProjectGroupDaoImpl.java:168)
at org.apache.maven.continuum.DefaultContinuum.executeAddProjectsFromMetadataActivity(DefaultContinuum.java:1689)
at org.apache.maven.continuum.DefaultContinuum.executeAddProjectsFromMetadataActivity(DefaultContinuum.java:1777)
at org.apache.maven.continuum.DefaultContinuum.addMavenTwoProject(DefaultContinuum.java:1358)
at org.apache.maven.continuum.web.action.AddMavenTwoProjectAction.doExecute(AddMavenTwoProjectAction.java:109)
at org.apache.maven.continuum.web.action.AddMavenProjectAction.execute(AddMavenProjectAction.java:189)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:404)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:267)
at org.apache.struts2.interceptor.BackgroundProcess$1.run(BackgroundProcess.java:56)
at java.lang.Thread.run(Unknown Source)