Bug 193245 Should block user to set content type property on the child element
After we switch from the slot to content element type property, all the rules that we applied to the slot before should be applied to the content element type property. When an element is extended from the library element, it should not be allowed to change the child element structure. So, when user call setProperty() to set the value of the content element type property, Model should throw out exception.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/command/PropertyCommandTest.java
* <tr>
 * <td>{@link #testInsertAndRemoveItem()}</td>
 * <td>undo and redo those two operations</td>
 * <td>after undo and redo operation , size of rules plus or reduce one</td>
 * </tr>
 * 
 * <tr>
 * <td></td>
 * <td>remove item from null structure list
 * 
 * </td>
 * <td>remove item from null list must throw out exception</td>
 * </tr>
 * 
 * <tr>
 * <td>{@link #testMoveItem()}</td>
 * <td>test move item operation from not null structure list</td>
 * <td>Matches the golden file.</td>
 * </tr>
 * 
 * <tr>
 * <td></td>
 * <td>undo and redo several times</td>
 * <td>Matches the golden file.</td>
 * </tr>
 * 
 * <tr>
 * <td></td>
 * <td>test move item operation from null structure list</td>
 * <td>Matches the golden file.</td>