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java.util.ConcurrentModificationException: null	at java.util.LinkedHashMap$LinkedHashIterator.nextEntry(LinkedHashMap.java:394)	at java.util.LinkedHashMap$KeyIterator.next(LinkedHashMap.java:405)	at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1067)	at org.obiba.magma.datasource.mongodb.MongoDBDatasource.drop(MongoDBDatasource.java:137)	at org.obiba.magma.support.AbstractDatasourceWrapper.drop(AbstractDatasourceWrapper.java:107)	at org.obiba.magma.support.AbstractDatasourceWrapper.drop(AbstractDatasourceWrapper.java:107)	at org.obiba.opal.project.ProjectsServiceImpl.delete(ProjectsServiceImpl.java:115)	at org.obiba.opal.web.project.ProjectResource.delete(ProjectResource.java:82)	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)	at java.lang.reflect.Method.invoke(Method.java:606)	at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:167)	at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:269)	at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:227)	at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:216)	at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:542)	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:524)	at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:126)	at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208)	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)	at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50)	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:652)	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1329)	at org.obiba.opal.server.httpd.OpalJettyServer$TransactionFilter$1.doInTransactionWithoutResult(OpalJettyServer.java:325)	at org.springframework.transaction.support.TransactionCallbackWithoutResult.doInTransaction(TransactionCallbackWithoutResult.java:33)	at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:131)	at org.obiba.opal.server.httpd.OpalJettyServer$TransactionFilter.doFilterInternal(OpalJettyServer.java:321)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1300)	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1300)	at org.obiba.opal.server.httpd.security.AuthenticationFilter.doFilterInternal(AuthenticationFilter.java:82)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1300)	at org.obiba.opal.server.httpd.OpalJettyServer$OpalVersionFilter.doFilterInternal(OpalJettyServer.java:305)	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)	at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1300)	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:445)	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1038)	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:374)	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:972)	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)	at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:52)	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)	at org.eclipse.jetty.server.Server.handle(Server.java:363)	at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:483)	at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:920)	at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:982)	at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:635)	at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)	at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)	at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:628)	at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)	at java.lang.Thread.run(Thread.java:724)