Worklight 6.1 JPA errors in log: can not start app

I have WL 6.1 Studio (on the top RAD 9.0.1) + WAS Liberty Profile 8.5.5.1 + WL 6.1 + Derby DB.
At some point in time I started receiving errors and my WL application failed to start, from WAS log it seems that problem with JPA (or JPA classes loading conflict)?
What can I check to fix it?
Below is the relevant fragment from the log file (application fails to start)
[4/1/14 12:29:56:077 VET] 00000020 com.ibm.ws.kernel.feature.internal.FeatureManager            A CWWKF0011I: The server server1 is ready to run a smarter planet.
[4/1/14 12:29:56:459 VET] 00000030 com.ibm.ws.session.WASSessionCore                            I SESN8501I: The session manager did not find a persistent storage location; HttpSession objects will be stored in the local application server's memory.
[4/1/14 12:29:56:465 VET] 00000030 com.ibm.ws.session.WASSessionCore                            I SESN0176I: A new session context will be created for application key default_host/MyProject
[4/1/14 12:29:56:477 VET] 00000030 com.ibm.ws.util                                              I SESN0172I: The session manager is using the Java default SecureRandom implementation for session ID generation.
[4/1/14 12:29:56:831 VET] 00000030 com.ibm.ws.cache.CacheServiceImpl                            I DYNA1056I: Dynamic Cache (object cache) initialized successfully.
[4/1/14 12:29:56:832 VET] 00000030 com.ibm.ws.cache.CacheServiceImpl                            I DYNA1056I: Dynamic Cache (object cache) initialized successfully.
[4/1/14 12:29:58:334 VET] 00000030 com.worklight.server.bundle.project.JeeProjectActivator      I FWLST0001I: Worklight home folder is C:\IBM\WebSphere\Liberty\usr\servers\server1\workarea\org.eclipse.osgi\bundles\76\data\temp\default_node\SMF_WebContainer\MyProject\MyProject [project MyProject]
[4/1/14 12:29:59:194 VET] 00000030 ingframework.context.support.FileSystemXmlApplicationContext I Refreshing org.springframework.context.support.FileSystemXmlApplicationContext@2bf82bf8: display name [org.springframework.context.support.FileSystemXmlApplicationContext@2bf82bf8]; startup date [Tue Apr 01 12:29:59 VET 2014]; root of context hierarchy
[4/1/14 12:29:59:275 VET] 00000030 rg.springframework.beans.factory.xml.XmlBeanDefinitionReader I Loading XML bean definitions from URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/spring-server-core.xml]
[4/1/14 12:29:59:397 VET] 00000030 rg.springframework.beans.factory.xml.XmlBeanDefinitionReader I Loading XML bean definitions from URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/core.xml]
[4/1/14 12:29:59:429 VET] 00000030 rg.springframework.beans.factory.xml.XmlBeanDefinitionReader I Loading XML bean definitions from URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/integration.xml]
[4/1/14 12:29:59:441 VET] 00000030 rg.springframework.beans.factory.xml.XmlBeanDefinitionReader I Loading XML bean definitions from URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/gadgets.xml]
[4/1/14 12:29:59:450 VET] 00000030 ngframework.beans.factory.support.DefaultListableBeanFactory I Overriding bean definition for bean 'gadgetCustomizedResourcesRoot': replacing [Generic bean: class [com.worklight.core.util.WorkingDirectory]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/gadgets.xml]] with [Generic bean: class [com.worklight.core.util.WorkingDirectory]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/spring-server-core.xml]]
[4/1/14 12:29:59:450 VET] 00000030 ngframework.beans.factory.support.DefaultListableBeanFactory I Overriding bean definition for bean 'gadgetResourcesRoot': replacing [Generic bean: class [com.worklight.core.util.WorkingDirectory]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/gadgets.xml]] with [Generic bean: class [com.worklight.core.util.WorkingDirectory]; scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; defined in URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/spring-server-core.xml]]
[4/1/14 12:29:59:452 VET] 00000030 ingframework.context.support.FileSystemXmlApplicationContext I Bean factory for application context [org.springframework.context.support.FileSystemXmlApplicationContext@2bf82bf8]: org.springframework.beans.factory.support.DefaultListableBeanFactory@7fa67fa6
[4/1/14 12:29:59:606 VET] 00000030 ngframework.beans.factory.support.DefaultListableBeanFactory I Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@7fa67fa6: defining beans [txManager,mailingService,WorkLightNotice,rssBrokerUtils,audit,GenericDAO,propertiesDAO,clusterSynchronizationDAO,taskCoordinator,taskManager,worklightAuthenticationService,authenticationDAO,ssoDAO,identityAssociationCleanupTask,ClusterDataSynchronizationTask,ssoExpiredLoginContextsCleanupTask,keyStoreManager,analyticsHttpService,invocationContextManager,notificationDAO,dataAccessService,shellResourcesService,pushReportsService,analyticsService,coreServiceManager,adapterManager,nodeProcessManager,deployService,notificationsSimulationManager,notificationDispatcher,factProcessingTask,PlatformUsageProcessingTask,notificationCleanupTask,WSSecurityService,gadgetDAO,deviceDAO,licenseTermsDAO,widgetService,platformUsageService,gfwProps,gadgetEnvironmentManager,gadgetResourcesRoot,gadgetCustomizedResourcesRoot,appVersionAccessService,DeployableFolderCleanupTask,applicationMetadataService,worklight-direct,rssBrokerDS,brokerSessionFactory,reportService,reportsDS,reportsBrokerDS,reportsSessionFactory,gadgetReportsDAO,notificationReportsDao,gadgetReportsService,analyticsFactService]; root of factory hierarchy
[4/1/14 12:29:59:786 VET] 00000030 com.worklight.server.bundle.api.WorklightConfiguration       I FWLSE4006I: Worklight Studio is running in 'development' mode. [project MyProject]
[4/1/14 12:30:01:409 VET] 00000030 ringframework.orm.jpa.LocalContainerEntityManagerFactoryBean I Building JPA container EntityManagerFactory for persistence unit 'WorklightPU'
[4/1/14 12:30:01:643 VET] 00000030 SystemErr                                                    R 16  WorklightPU  WARN   [Default Executor-thread-5] openjpa.Runtime - An error occurred while registering a ClassTransformer with PersistenceUnitInfo: name 'WorklightPU', root URL [file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar]. The error has been consumed. To see it, set your openjpa.Runtime log level to TRACE. Load-time class transformation will not be available.
[4/1/14 12:30:02:115 VET] 00000030 SystemErr                                                    R 489  WorklightPU  INFO   [Default Executor-thread-5] openjpa.Runtime - Starting OpenJPA 1.2.2
[4/1/14 12:30:02:169 VET] 00000030 SystemErr                                                    R 542  WorklightPU  INFO   [Default Executor-thread-5] openjpa.jdbc.JDBC - Using dictionary class "org.apache.openjpa.jdbc.sql.HSQLDictionary".
[4/1/14 12:30:03:265 VET] 00000030 com.worklight.server.database.api.WorklightDataSource        I FWLSE0187I: jdbc/WorklightReportsDS data source is disabled. No connection opened.  [project MyProject]
[4/1/14 12:30:03:273 VET] 00000030 ringframework.orm.jpa.LocalContainerEntityManagerFactoryBean I Building JPA container EntityManagerFactory for persistence unit 'WorklightReportsPU'
[4/1/14 12:30:03:278 VET] 00000030 SystemErr                                                    R 0  WorklightReportsPU  WARN   [Default Executor-thread-5] openjpa.Runtime - An error occurred while registering a ClassTransformer with PersistenceUnitInfo: name 'WorklightReportsPU', root URL [file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar]. The error has been consumed. To see it, set your openjpa.Runtime log level to TRACE. Load-time class transformation will not be available.
[4/1/14 12:30:03:292 VET] 00000030 com.worklight.report.impl.GadgetReportsServiceImpl           I FWLSE0186I: Application raw reports are disabled. [project MyProject]
[4/1/14 12:30:03:676 VET] 00000030 ngframework.beans.factory.support.DefaultListableBeanFactory I Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@7fa67fa6: defining beans [txManager,mailingService,WorkLightNotice,rssBrokerUtils,audit,GenericDAO,propertiesDAO,clusterSynchronizationDAO,taskCoordinator,taskManager,worklightAuthenticationService,authenticationDAO,ssoDAO,identityAssociationCleanupTask,ClusterDataSynchronizationTask,ssoExpiredLoginContextsCleanupTask,keyStoreManager,analyticsHttpService,invocationContextManager,notificationDAO,dataAccessService,shellResourcesService,pushReportsService,analyticsService,coreServiceManager,adapterManager,nodeProcessManager,deployService,notificationsSimulationManager,notificationDispatcher,factProcessingTask,PlatformUsageProcessingTask,notificationCleanupTask,WSSecurityService,gadgetDAO,deviceDAO,licenseTermsDAO,widgetService,platformUsageService,gfwProps,gadgetEnvironmentManager,gadgetResourcesRoot,gadgetCustomizedResourcesRoot,appVersionAccessService,DeployableFolderCleanupTask,applicationMetadataService,worklight-direct,rssBrokerDS,brokerSessionFactory,reportService,reportsDS,reportsBrokerDS,reportsSessionFactory,gadgetReportsDAO,notificationReportsDao,gadgetReportsService,analyticsFactService]; root of factory hierarchy
[4/1/14 12:30:03:678 VET] 00000030 ringframework.orm.jpa.LocalContainerEntityManagerFactoryBean I Closing JPA EntityManagerFactory for persistence unit 'WorklightReportsPU'
[4/1/14 12:30:03:680 VET] 00000030 ringframework.orm.jpa.LocalContainerEntityManagerFactoryBean I Closing JPA EntityManagerFactory for persistence unit 'WorklightPU'
[4/1/14 12:30:04:038 VET] 00000030 hsqldb.db.HSQLDB44FE2B1271.ENGINE                            I Database closed
[4/1/14 12:30:04:150 VET] 00000030 com.worklight.server.bundle.project.JeeProjectActivator      E FWLST0003E: ========= Failed starting project /MyProject [project MyProject]
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'notificationDispatcher' defined in URL [wsjar:file:/C:/IBM/WebSphere/Liberty/usr/shared/resources/worklight-jee-library-6.1.0.jar!/conf/integration.xml]: Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1338)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:473)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBeanFactory.java:409)
    at java.security.AccessController.doPrivileged(AccessController.java:224)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:380)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:264)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:261)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:185)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:429)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:728)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:380)
    at com.worklight.server.bundle.project.JeeProjectActivator.loadSpringConfiguration(JeeProjectActivator.java:291)
    at com.worklight.server.bundle.project.JeeProjectActivator.contextInitialized(JeeProjectActivator.java:146)
    at com.ibm.ws.webcontainer.webapp.WebApp.notifyServletContextCreated(WebApp.java:2220)
    at com.ibm.ws.webcontainer.webapp.WebApp.initialize(WebApp.java:960)
    at com.ibm.ws.webcontainer.webapp.WebApp.initialize(WebApp.java:6049)
    at com.ibm.ws.webcontainer.osgi.DynamicVirtualHost.startWebApp(DynamicVirtualHost.java:421)
    at com.ibm.ws.webcontainer.osgi.DynamicVirtualHost.createRunnableHandler(DynamicVirtualHost.java:241)
    at com.ibm.ws.http.internal.VirtualHostImpl.discriminate(VirtualHostImpl.java:182)
    at com.ibm.ws.http.dispatcher.internal.channel.HttpDispatcherLink.ready(HttpDispatcherLink.java:169)
    at com.ibm.ws.http.channel.internal.inbound.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:448)
    at com.ibm.ws.http.channel.internal.inbound.HttpInboundLink.handleNewRequest(HttpInboundLink.java:382)
    at com.ibm.ws.http.channel.internal.inbound.HttpInboundLink.processRequest(HttpInboundLink.java:282)
    at com.ibm.ws.http.channel.internal.inbound.HttpInboundLink.ready(HttpInboundLink.java:253)
    at com.ibm.ws.tcpchannel.internal.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:174)
    at com.ibm.ws.tcpchannel.internal.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:83)
    at com.ibm.ws.tcpchannel.internal.WorkQueueManager.requestComplete(WorkQueueManager.java:502)
    at com.ibm.ws.tcpchannel.internal.WorkQueueManager.attemptIO(WorkQueueManager.java:550)
    at com.ibm.ws.tcpchannel.internal.WorkQueueManager.workerRun(WorkQueueManager.java:899)
    at com.ibm.ws.tcpchannel.internal.WorkQueueManager$Worker.run(WorkQueueManager.java:981)
    at com.ibm.ws.threading.internal.Worker.executeWork(Worker.java:439)
    at com.ibm.ws.threading.internal.Worker.run(Worker.java:421)
    at java.lang.Thread.run(Thread.java:736)
Caused by: java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others
    at sun.misc.ProxyGenerator.checkReturnTypes(ProxyGenerator.java:622)
    at sun.misc.ProxyGenerator.generateClassFile(ProxyGenerator.java:432)
    at sun.misc.ProxyGenerator.generateProxyClass(ProxyGenerator.java:318)
    at java.lang.reflect.Proxy.getProxyClass(Proxy.java:513)
    at java.lang.reflect.Proxy.newProxyInstance(Proxy.java:593)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator.createProxy(ExtendedEntityManagerCreator.java:265)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator.createProxy(ExtendedEntityManagerCreator.java:230)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator.createApplicationManagedEntityManager(ExtendedEntityManagerCreator.java:111)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean$ManagedEntityManagerFactoryInvocationHandler.invoke(AbstractEntityManagerFactoryBean.java:437)
    at $Proxy22.createEntityManager(Unknown Source)
    at org.springframework.orm.jpa.EntityManagerFactoryAccessor.createEntityManager(EntityManagerFactoryAccessor.java:116)
    at org.springframework.orm.jpa.JpaTemplate.execute(JpaTemplate.java:177)
    at org.springframework.orm.jpa.JpaTemplate.executeFind(JpaTemplate.java:151)
    at org.springframework.orm.jpa.JpaTemplate.findByNamedQuery(JpaTemplate.java:343)
    at com.worklight.server.database.api.JpaDaoHelper.executeQuery(JpaDaoHelper.java:36)
    at com.worklight.integration.notification.NotificationDAO.getRegisteredApplications(NotificationDAO.java:151)
    at com.worklight.integration.notification.Dispatcher.init(Dispatcher.java:67)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
    at java.lang.reflect.Method.invoke(Method.java:611)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeCustomInitMethod(AbstractAutowireCapableBeanFactory.java:1414)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1375)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1335)
    ... 34 more

[4/1/14 12:30:04:340 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Deploying javax.ws.rs.core.Application: class com.worklight.console.application.ConsoleAPIApplication
[4/1/14 12:30:04:343 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.DevicesController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:343 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.LicenseTermsController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:343 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.AdaptersController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:343 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.ApplicationsController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:344 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.UIController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:344 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.PushController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:344 VET] 00000030 org.jboss.resteasy.spi.ResteasyDeployment                    I Adding singleton resource com.worklight.console.controllers.UsersController from Application javax.ws.rs.core.Application
[4/1/14 12:30:04:567 VET] 00000020 com.ibm.ws.logging.internal.impl.IncidentImpl                I FFDC1015I: An FFDC Incident has been created: "javax.servlet.ServletException: Worklight Console initialization failed.Logged Exception: java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter 144" at ffdc_14.04.01_12.30.04.0.log
[4/1/14 12:30:04:646 VET] 00000020 com.ibm.ws.logging.internal.impl.IncidentImpl                I FFDC1015I: An FFDC Incident has been created: "javax.servlet.ServletException: Worklight Console initialization failed.Logged Exception: java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter 82" at ffdc_14.04.01_12.30.04.1.log
[4/1/14 12:30:04:648 VET] 00000020 com.ibm.ws.logging.internal.impl.IncidentImpl                I FFDC1015I: An FFDC Incident has been created: "javax.servlet.ServletException: Worklight Console initialization failed.Logged Exception: java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters 1064" at ffdc_14.04.01_12.30.04.2.log
[4/1/14 12:30:04:665 VET] 00000020 com.ibm.ws.webcontainer.webapp                               E SRVE0315E: An execption occurred: com.ibm.ws.webcontainer.webapp.WebAppErrorReport: javax.servlet.ServletException: Worklight Console initialization failed.Logged Exception: java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others
    at com.ibm.ws.webcontainer.webapp.WebAppErrorReport.constructErrorReport(WebAppErrorReport.java:153)
    at com.ibm.ws.webcontainer.webapp.WebAppErrorReport.constructErrorReport(WebAppErrorReport.java:194)
    at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1098)
    at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:4510)
    at com.ibm.ws.webcontainer.osgi.DynamicVirtualHost$2.handleRequest(DynamicVirtualHost.java:282)
    at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:954)
    at com.ibm.ws.webcontainer.osgi.DynamicVirtualHost$2.run(DynamicVirtualHost.java:252)
    at com.ibm.ws.http.dispatcher.internal.channel.HttpDispatcherLink$TaskWrapper.run(HttpDispatcherLink.java:584)
    at com.ibm.ws.threading.internal.Worker.executeWork(Worker.java:439)
    at com.ibm.ws.threading.internal.Worker.run(Worker.java:421)
    at java.lang.Thread.run(Thread.java:736)
Caused by: javax.servlet.ServletException: Worklight Console initialization failed.Logged Exception: java.lang.IllegalArgumentException: methods with same signature detach(java.lang.Object) but incompatible return types: void and others
    at com.worklight.core.auth.impl.AuthenticationFilter.verifyServletInitialized(AuthenticationFilter.java:300)
    at com.worklight.core.auth.impl.AuthenticationFilter.doFilter(AuthenticationFilter.java:111)
    at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:194)
    at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:85)
    at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:968)
    at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1056)
    ... 8 more
The exception is due to a conflict issue with classes from the Liberty runtime. The classes that are loaded depend on the feature you have defined in the Liberty profile server.xml file. Conflict occurs with Worklight for example when open-jpa and jax-rs features are enabled (and setting parentLast delegation doesn't resolve the problem) Which feature do you use ?