Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: TestPkg.AppsDefinition cannot be cast to Core.KAProvider
    at Core.MainForm.appsTree_MouseClicked(MainForm.java:305)
    at Core.MainForm$1.mouseClicked(MainForm.java:53)
    at java.awt.AWTEventMulticaster.mouseClicked(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$000(Unknown Source)
    at java.awt.EventQueue$1.run(Unknown Source)
    at java.awt.EventQueue$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$2.run(Unknown Source)
    at java.awt.EventQueue$2.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Class c = this.pluginManager.Read(apps.get(sel.toString())); //Тут в методе Read работает Classloader. Срабатывает
Constructor constructor = c.getConstructor(); //Срабатывает
Object obj = constructor.newInstance(); //Срабатывает
KAProvider man = (KAProvider)obj; // Кастим к интерфейсу. Не срабатывает

public class AppsDefinition implements KAProvider{
 
    private TestlFrame tf;
    private LinkManager linkManager;
 
    public void Start(Object src, LinkManager lm)
    {
        this.linkManager = lm;
        this.tf = new TestlFrame(this);
        ((JDesktopPane) src).add(this.tf);
        this.tf.setVisible(true);
 
    }
 
    public Connection GetConnection() {
        return this.linkManager.GetConnection();
    }
 
    public int GetOEBSUserID() {
        return this.linkManager.GetOEBSUserID();
    }
 
    public int GetUserID() {
        return this.linkManager.GetUserID();
    }
 
    public boolean GetAuthState() {
        return this.linkManager.GetAuthState();
    }
}

import java.sql.Connection;
 
public interface KAProvider {
 
    public void Start(Object src, LinkManager lm);
 
    public Connection GetConnection();
 
    public int GetOEBSUserID();
 
    public int GetUserID();
 
    public boolean GetAuthState();
}