java.lang.VerifyError: class com... overrides final method getCellRenderer.(II)Ljavax/swing/table/TableCellRenderer

During the startup of a webapp I get really lots of these errors:

09:02:08,652 WARN [ClassLoaderManager] Unexpected error during load of:com.foo.bar.MyTable: java.lang.VerifyError: class com.foo.bar.MyTable overrides final method getCellRenderer.(II)Ljavax/swing/table/TableCellRenderer;
at java.lang.ClassLoader.defineClass1(Native Method) [:1.6.0_16]
at java.lang.ClassLoader.defineClass(ClassLoader.java:621) [:1.6.0_16]
at org.jboss.classloader.spi.base.BaseClassLoader.access$200(BaseClassLoader.java:52) [jboss-classloader.jar:2.2.0.Alpha8]
...

The class MyTable extends from FoobarTable and FoobarTable extends from JTable... I'm little bit confused about the error message, because
I've got two getCellRenderer-methods. One of them overrides these one in JTable, the other one is private in both classes (MyTable and FoobarTable).
But no one of them is final.

Looks like:

public class FoobarTable extends JTable {
@Override
public TableCellRenderer getCellRenderer(int row, int column)

{ ... }
private TableCellRenderer getCellRenderer(Class x){ ... }

}

public class MyTable extends FoobarTable {
@Override
public TableCellRenderer getCellRenderer(int row, int column)

{ ... }
private TableCellRenderer getCellRenderer(Class x){ ... }

}