### Question:
RollupAdapter implements GriffonPivotAdapter, org.apache.pivot.wtk.RollupListener { public void collapsibleChanged(org.apache.pivot.wtk.Rollup arg0) { if (collapsibleChanged != null) { collapsibleChanged.call(arg0); } }  CallableWithArgs<Void> getContentChanged(); CallableWithArgs<Void> getCollapsibleChanged(); CallableWithArgs<Void> getHeadingChanged(); void setContentChanged(CallableWithArgs<Void> contentChanged); void setCollapsibleChanged(CallableWithArgs<Void> collapsibleChanged); void setHeadingChanged(CallableWithArgs<Void> headingChanged); void contentChanged(org.apache.pivot.wtk.Rollup arg0, org.apache.pivot.wtk.Component arg1); void collapsibleChanged(org.apache.pivot.wtk.Rollup arg0); void headingChanged(org.apache.pivot.wtk.Rollup arg0, org.apache.pivot.wtk.Component arg1);  }### Answer:
@Test public void testCollapsibleChanged() { final boolean[] invoked = new boolean[1]; CallableWithArgs<Void> callable = new CallableWithArgs<Void>() { public Void call(Object... args) { invoked[0] = true; return null; } }; assertNull(adapter.getCollapsibleChanged()); adapter.collapsibleChanged(null); assertFalse(invoked[0]); adapter.setCollapsibleChanged(callable); adapter.collapsibleChanged(null); assertTrue(invoked[0]); }