JSF Converter - NullPointerException

Question

I have following converter code:

@FacesConverter("konverter")
public class Konverter implements Converter {

@EJB
private BenutzerAendernLocal benutzer;

@Override
public Object getAsObject(FacesContext fc, UIComponent uic, String value) {
    if (value != null && value.trim().length() > 0) {
        try {
            System.out.println("KONVERTER: " + Integer.parseInt(value));

            return benutzer.finde(Integer.parseInt(value));
        } catch (NumberFormatException e) {
            throw new ConverterException(
                    new FacesMessage(FacesMessage.SEVERITY_ERROR, "Konvertier Fehler", "Nicht valide"));
        }
    } else {
        return null;
    }
 }

@Override
public String getAsString(FacesContext fc, UIComponent uic, Object object) {
    if (object != null) {
        return String.valueOf(((Benutzer) object).getId());
    } else {
        return null;
    }
}

}

And the code in my @Stateless SessionBean:

@Override
public Benutzer finde(Integer id) {
    try {
        Benutzer b = em.find(Benutzer.class, id);
        return b;
    } catch (NoResultException e) {
        return null;
    }

}

The Problem that i have is that in the 'getAsObject()' Method in the Konverter class at the return statement i got a NullPointerException. Strange - in the System.out i got the right id so the value isn't null.

Error:

2016-09-15T10:43:55.622+0200|Schwerwiegend: java.lang.NullPointerException at de.Bean.Konverter.getAsObject(Konverter.java:26) at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getConvertedValue(HtmlBasicInputRenderer.java:171) at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectOneValue(MenuRenderer.java:201) at com.sun.faces.renderkit.html_basic.MenuRenderer.getConvertedValue(MenuRenderer.java:318) at org.primefaces.component.selectonelistbox.SelectOneListboxRenderer.getConvertedValue(SelectOneListboxRenderer.java:36) at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1045) at javax.faces.component.UIInput.validate(UIInput.java:975) at javax.faces.component.UIInput.executeValidate(UIInput.java:1248) at javax.faces.component.UIInput.processValidators(UIInput.java:712) at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261) at org.primefaces.component.panel.Panel.processValidators(Panel.java:287) at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261) at org.primefaces.component.dialog.Dialog.processValidators(Dialog.java:403) at javax.faces.component.UIForm.processValidators(UIForm.java:253) at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261) at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1261) at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1195) at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76) at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:658) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160) at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:416) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:283) at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167) at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:206) at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:180) at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235) at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119) at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284) at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201) at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133) at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112) at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77) at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:526) at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56) at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137) at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:591) at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:571) at java.lang.Thread.run(Thread.java:745)