The error is raised when the response of a particular request is treated. The request is particular because it receives a proxy which uses java generics in its declaration. It's the only case so far in my application.
SEVERE: Unexpected error
java.lang.NullPointerException
at com.google.web.bindery.autobean.vm.impl.MethodPropertyContext.traverse(MethodPropertyContext.java:102)
at com.google.web.bindery.autobean.vm.impl.MethodPropertyContext.accept(MethodPropertyContext.java:75)
at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl$PropertyCoderCreator.maybeCreateCoder(AutoBeanCodexImpl.java:353)
at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl$PropertyCoderCreator.visitReferenceProperty(AutoBeanCodexImpl.java:341)
at com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.traverseProperties(ProxyAutoBean.java:295)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.traverse(AbstractAutoBean.java:166)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.accept(AbstractAutoBean.java:101)
at com.google.web.bindery.autobean.shared.impl.AutoBeanCodexImpl.doCoderFor(AutoBeanCodexImpl.java:521)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.setProperty(AbstractAutoBean.java:276)
at com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.setProperty(ProxyAutoBean.java:224)
at com.google.web.bindery.autobean.vm.impl.BeanPropertyContext.set(BeanPropertyContext.java:44)
at com.google.web.bindery.requestfactory.server.Resolver$1.visitValueProperty(Resolver.java:371)
at com.google.web.bindery.autobean.vm.impl.ProxyAutoBean.traverseProperties(ProxyAutoBean.java:260)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.traverse(AbstractAutoBean.java:166)
at com.google.web.bindery.autobean.shared.impl.AbstractAutoBean.accept(AbstractAutoBean.java:101)
at com.google.web.bindery.requestfactory.server.Resolver.resolveClientProxy(Resolver.java:323)
at com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:418)
at com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:442)
at com.google.web.bindery.requestfactory.server.Resolver.resolveClientValue(Resolver.java:196)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.processInvocationMessages(SimpleRequestProcessor.java:451)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:217)
at com.google.web.bindery.requestfactory.server.SimpleRequestProcessor.process(SimpleRequestProcessor.java:125)
at com.google.web.bindery.requestfactory.server.RequestFactoryServlet.doPost(RequestFactoryServlet.java:118)