Java – ClassNotFoundException: org.dom4j.DocumentException

I am trying to debug (F11 on Eclipse) a java GUI application I inherited but while the application runs fine (minus a tiny fix I need to apply) outside of the Eclipse IDE, it produces the following exception when launched from Eclipse (either F11 or Ctrl+F11):

Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: org/dom4j/DocumentException
    at com.example.myapp.LoginWindow.buildHibernateConfig(LoginWindow.java:178)
    at com.example.myapp.LoginWindow.actionPerformed(LoginWindow.java:141)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.AbstractButton.doClick(AbstractButton.java:357)
    at javax.swing.plaf.basic.BasicRootPaneUI$Actions.actionPerformed(BasicRootPaneUI.java:191)
    at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1639)
    at javax.swing.JComponent.processKeyBinding(JComponent.java:2859)
    at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:267)
    at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:216)
    at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2936)
    at javax.swing.JComponent.processKeyBindings(JComponent.java:2928)
    at javax.swing.JComponent.processKeyEvent(JComponent.java:2822)
    at java.awt.Component.processEvent(Component.java:6074)
    at java.awt.Container.processEvent(Container.java:2039)
    at java.awt.Component.dispatchEventImpl(Component.java:4660)
    at java.awt.Container.dispatchEventImpl(Container.java:2097)
    at java.awt.Component.dispatchEvent(Component.java:4488)
    at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1856)
    at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:722)
    at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1000)
    at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:865)
    at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:686)
    at java.awt.Component.dispatchEventImpl(Component.java:4532)
    at java.awt.Container.dispatchEventImpl(Container.java:2097)
    at java.awt.Window.dispatchEventImpl(Window.java:2489)
    at java.awt.Component.dispatchEvent(Component.java:4488)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:668)
    at java.awt.EventQueue.access$400(EventQueue.java:81)
    at java.awt.EventQueue$2.run(EventQueue.java:627)
    at java.awt.EventQueue$2.run(EventQueue.java:625)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
    at java.awt.EventQueue$3.run(EventQueue.java:641)
    at java.awt.EventQueue$3.run(EventQueue.java:639)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:638)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: java.lang.ClassNotFoundException: org.dom4j.DocumentException
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    ... 47 more

My initial search on this found that the dom4j library may be missing but adding it to the pom.xml:

    <dependency>
        <groupId>net.sourceforge.saxon</groupId>
        <artifactId>saxon</artifactId>
        <version>9.1.0.8</version>
    </dependency>        
   <dependency>
        <groupId>dom4j</groupId>
        <artifactId>dom4j</artifactId>
        <version>1.6.1</version>
    </dependency>
    </dependencies>

Did not solve the problem.

Any idea why I am getting this exception (only when launching from Eclipse) and how to solve this problem?

BTW, the saxson dependency was added only because trying to use the latest dom4j resulted in unresolved dependencies when building. But since I downgraded to dom4j 1.6.1 I could eliminate the saxon dependency so the pom.xml file only contains now:

   <dependency>
        <groupId>dom4j</groupId>
        <artifactId>dom4j</artifactId>
        <version>1.6.1</version>
    </dependency>
    </dependencies>