The spec for method javax.swing.plaf.LayerUI.getScrollableTracksViewportHeight() says:

    /**
     * Returns {@code false} to indicate that the height of the viewport does not
     * determine the height of the layer, unless the preferred height
     * of the layer is smaller than the height of the viewport.
     */

Failing JCK tests:
api/javax_swing/plaf/LayerUI/index.html#General[getScrollableTracksViewportHeight_viewPort]
api/javax_swing/plaf/LayerUI/index.html#General[getScrollableTracksViewportWidth_viewPort]

Platform: ALL
JDK 7 b75: FAIL
JDK 7 b70: PASS


Please see the following minimized code below (for getScrollableTracksViewportHeight, getScrollableTracksViewportWidth behaves the same way):
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import javax.swing.*;
import javax.swing.plaf.LayerUI;
import java.awt.*;

/**
 * Verifies that method returns false to indicate that the height of the viewport does not
 * determine the height of the layer, unless the preferred height
 * of the layer is smaller than the height of the viewport
 */
public class LayerUI_getSTVpHeight {
    public static void main(String[] args) {
        int layerPrefSizeHeight = 50;
        final int vpHeight = 100;
        JLayer layer = new JLayer();
        layer.setPreferredSize(new Dimension(0, layerPrefSizeHeight));
        JViewport viewport = new JViewport() {
            @Override
            public int getHeight() {
                return vpHeight;
            }
        };
        viewport.setView(layer);
        System.out.println("vpHeight > layerPrefSizeHeight = " + (vpHeight > layerPrefSizeHeight));
        System.out.println("getScrollableTracksViewportHeight(layer) = " +
                new LayerUI().getScrollableTracksViewportHeight(layer));
    }
}
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