title: org.apache.tomcat.SimpleInstanceManager cannot be cast to org.apache.tomcat.InstanceManager
body: <p>I trying to upgrade my app to GWT 2.8 and Java 8 but no matter what I encounter with this problem. Note that I am using embedded Jetty.</p>
  
  <pre><code>org.apache.jasper.JasperException: java.lang.ClassCastException: org.apache.tomcat.SimpleInstanceManager cannot be cast to org.apache.tomcat.InstanceManager
      at org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:585)
      at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:396)
      at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:405)
      at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:349)
      at org.eclipse.jetty.jsp.JettyJspServlet.service(JettyJspServlet.java:107)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
      at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:812)
      at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:587)
      at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
      at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577)
      at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223)
      at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127)
      at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)
      at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
      at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061)
      at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
      at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
      at org.eclipse.jetty.server.handler.RequestLogHandler.handle(RequestLogHandler.java:95)
      at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
      at org.eclipse.jetty.server.Server.handle(Server.java:499)
      at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311)
      at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:257)
      at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544)
      at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635)
      at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555)
      at java.lang.Thread.run(Thread.java:745)
  Caused by: java.lang.ClassCastException: org.apache.tomcat.SimpleInstanceManager cannot be cast to org.apache.tomcat.InstanceManager
      at org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(InstanceManagerFactory.java:29)
      at org.apache.jsp.index_jsp._jspInit(index_jsp.java:32)
      at org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:49)
      at org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:180)
  at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
  </code></pre>
  
  <p>Lots of the dependencies coming from GWT 2.8 but here is the pom.xml:</p>
  
  <pre><code>&lt;build&gt;
  &lt;sourceDirectory&gt;src&lt;/sourceDirectory&gt;
  &lt;testSourceDirectory&gt;test&lt;/testSourceDirectory&gt;
    &lt;outputDirectory&gt;war/WEB-INF/classes&lt;/outputDirectory&gt;
  &lt;resources&gt;
          &lt;resource&gt;
      &lt;directory&gt;src&lt;/directory&gt;
      &lt;excludes&gt;
        &lt;exclude&gt;**/*.java&lt;/exclude&gt;
      &lt;/excludes&gt;
    &lt;/resource&gt;
  &lt;/resources&gt;
  &lt;plugins&gt;
    &lt;plugin&gt;
      &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
      &lt;version&gt;2.3.2&lt;/version&gt;
      &lt;configuration&gt;
          &lt;source&gt;1.8&lt;/source&gt;
          &lt;target&gt;1.8&lt;/target&gt;
      &lt;/configuration&gt;
    &lt;/plugin&gt;
  &lt;/plugins&gt;
   &lt;/build&gt;
  &lt;dependencies&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.apache.commons&lt;/groupId&gt;
      &lt;artifactId&gt;commons-compress&lt;/artifactId&gt;
      &lt;version&gt;1.10&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;commons-fileupload&lt;/groupId&gt;
      &lt;artifactId&gt;commons-fileupload&lt;/artifactId&gt;
      &lt;version&gt;1.2.2&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.vectomatic&lt;/groupId&gt;
      &lt;artifactId&gt;lib-gwt-file&lt;/artifactId&gt;
      &lt;version&gt;0.3.1&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.apache.commons&lt;/groupId&gt;
      &lt;artifactId&gt;commons-lang3&lt;/artifactId&gt;
      &lt;version&gt;3.1&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;com.asimalp.commons&lt;/groupId&gt;
      &lt;artifactId&gt;asimalp-commons&lt;/artifactId&gt;
      &lt;version&gt;3.0.0&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;com.asimalp.poi&lt;/groupId&gt;
      &lt;artifactId&gt;asimalp-poi&lt;/artifactId&gt;
      &lt;version&gt;1.0.0&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;com.google.gwt&lt;/groupId&gt;
      &lt;artifactId&gt;gwt-visualization&lt;/artifactId&gt;
      &lt;version&gt;1.1.2&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.postgresql&lt;/groupId&gt;
      &lt;artifactId&gt;postgresql&lt;/artifactId&gt;
      &lt;version&gt;9.3-1101-jdbc41&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;com.microsoft.sqlserver&lt;/groupId&gt;
      &lt;artifactId&gt;sqljdbc4&lt;/artifactId&gt;
      &lt;version&gt;4.0&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;com.google.guava&lt;/groupId&gt;
      &lt;artifactId&gt;guava-gwt&lt;/artifactId&gt;
      &lt;version&gt;20.0&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.apache.axis&lt;/groupId&gt;
      &lt;artifactId&gt;axis&lt;/artifactId&gt;
      &lt;version&gt;1.4&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;javax.xml&lt;/groupId&gt;
      &lt;artifactId&gt;jaxrpc&lt;/artifactId&gt;
      &lt;version&gt;1.1&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;org.eclipse.birt.runtime.3_7_1&lt;/groupId&gt;
      &lt;artifactId&gt;javax.wsdl&lt;/artifactId&gt;
      &lt;version&gt;1.5.1&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;dom4j&lt;/groupId&gt;
      &lt;artifactId&gt;dom4j&lt;/artifactId&gt;
      &lt;version&gt;1.6.1&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;javax.comm&lt;/groupId&gt;
      &lt;artifactId&gt;comm&lt;/artifactId&gt;
      &lt;version&gt;2.0&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;ojdbc7&lt;/groupId&gt;
      &lt;artifactId&gt;ojdbc7&lt;/artifactId&gt;
      &lt;version&gt;12.1.0.2&lt;/version&gt;
  &lt;/dependency&gt;
  &lt;dependency&gt;
      &lt;groupId&gt;com.google.code.gson&lt;/groupId&gt;
      &lt;artifactId&gt;gson&lt;/artifactId&gt;
      &lt;version&gt;2.7&lt;/version&gt;
  &lt;/dependency&gt;
    &lt;/dependencies&gt;
  </code></pre>
  
  <p>Any help would be appreciated.</p>