Considering the following hierarchy of components:

frame[ comp1 container[ comp2 comp3 ] comp4 ]

where <frame> is the parent of <comp1>, <container> and <comp4>
and <container> is the parent of <comp2> and <comp3>.

<frame> has ContainerFocusTraversalPolicy.

In such a case the cycle of traversable components looks as follows:

<frame> -> <comp1> -> <container> -> <comp2> -> <comp3> -> <comp4>.

However, if we make <container> focus traversal policy provider,
the cycle changes in the following way:

<frame> -> <comp1> -> <container>.

I.e. a) focus doesn't go into the provider,
     b) focus jumps over <comp4>.

In DefaultFocusTraversalPolicy, the same problems are revealed
when making <container> focusable.

Swing's policies (SortingFTP and LayoutFTP) also follows the
behaviour pointed by (a), with <container> set focusable.

This behaviour is considered illogical. The content of the provider
is unreachable in forward traversing. The behaviour in this case
shouldn't be different from the behaviour of a simple container.

Below is the testcase:

================================
import java.awt.*;
import java.awt.event.*;

public class AWTPolicy {
    
    public static void main(String[] args) {
        final Frame f = new Frame("Frame");
        final Panel p = new Panel();
        Button b0 = new Button("comp1");
        Button b1 = new Button("comp2");
        Button b2 = new Button("comp3");
        Button b3 = new Button("comp4");

        f.setFocusTraversalPolicy(new ContainerOrderFocusTraversalPolicy());
        f.addFocusListener(new FocusAdapter() {
                public void focusGained(FocusEvent e) {
                    System.err.println("Frame got focus.");
                }
            });

        if (args.length > 0 && "provider".equals(args[0])) {
            p.setFocusTraversalPolicyProvider(true);
        }

        p.addFocusListener(new FocusListener() {
                public void focusGained(FocusEvent e) {
                    p.setBackground(Color.red);
                    System.err.println("Panel got focus.");
                }
                public void focusLost(FocusEvent e) {
                    p.setBackground(Color.gray);
                }
            });
        p.setBackground(Color.gray);

        f.add(b0);
        p.add(b1);
        p.add(b2);
        f.add(p);
        f.add(b3);

        f.setLayout(new FlowLayout());
        f.pack();
        f.setVisible(true);
    }
}
==================================

Run the test and try to forward traverse focus though the whole cycle.
Then run the test with "provider" argument and find the cycle changed.