JASS implementation in JSF + Tomcat

I want to create authentication for login in my project, but when I try to login, the java.lang.NullPointerException error appears

Error Log

javax.faces.el.EvaluationException: java.lang.NullPointerException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
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:646)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at br.com.fastchoice.util.FacesUtil.getMensagemI18n(FacesUtil.java:13)
at br.com.fastchoice.bean.SegurancaBean.logar(SegurancaBean.java:23)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.el.parser.AstValue.invoke(AstValue.java:278)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:273)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 28 more

Class FacesUtil

public class FacesUtil {

public static String getMensagemI18n(String chave) {
    FacesContext context = FacesContext.getCurrentInstance();
    String msg = context.getApplication().getResourceBundle(context, "msg").getString(chave);
    return msg;
}

public static void adicionarMensagem(Severity tipo, String msg) {
    FacesContext.getCurrentInstance().addMessage(null, 
            new FacesMessage(tipo, msg, msg));
}

public static Object getRequestAttribute(String name) {
    FacesContext facesContext = FacesContext.getCurrentInstance();
    ExternalContext externalContext = facesContext.getExternalContext();
    HttpServletRequest request = (HttpServletRequest) externalContext.getRequest();
    return request.getAttribute(name);
}

}

Security ClassBean

public class SegurancaBean {

private String usuario;
private String senha;

public String logar() {
    try {
        this.getRequest().login(this.usuario, this.senha);
        return "Home?faces-redirect=true";
    } catch (ServletException e) {
        FacesUtil.adicionarMensagem(FacesMessage.SEVERITY_ERROR, 
                FacesUtil.getMensagemI18n("username_password_does_not_match"));
        return null;
    }
}

public String sair() throws ServletException {
    this.getRequest().logout();
    return "Login?faces-redirect=true";
}

private HttpServletRequest getRequest() {
    FacesContext context = FacesContext.getCurrentInstance();
    return (HttpServletRequest) context.getExternalContext().getRequest();
}

public String getUsuario() {
    return usuario;
}
public void setUsuario(String usuario) {
    this.usuario = usuario;
}
public String getSenha() {
    return senha;
}
public void setSenha(String senha) {
    this.senha = senha;
}

}