Bug 154828 Item from library contant user properties can't delete
Details: Item from library contant user properties can't delete Step: 1.New a library. 2.Add a label and add a user properites. 3.Public the library. 4.New a report design and use the library 5.Drop the label from library explorer into layout. 6.Try to delete it. Actual result: The label from library contant user properties can't be delete. Exception reuslt: The label can be delete.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
if ( referred.isStyle( ) )
				{
					StyleCommand clientCmd = new StyleCommand( module, client );
					clientCmd.setStyleElement( (DesignElement) null );
				}
				else
				{
					PropertyCommand cmd = new PropertyCommand( module, client );
					cmd.setProperty( ref.propName, null );
				}
			}
		}
	}
	/**
	 * Clears references of elements that are referred by the to-be-deleted
	 * element, except for extends and style element references. Unlike the
	 * method {@link #adjustReferenceClients(ReferenceableElement,boolean)},
	 * this method removes references from those elements that are referred.
	 * 
	 * @param element
	 *            the element to be deleted
	 * 
	 */
	private void adjustReferredClients( DesignElement element )
	{
		List propDefns = element.getPropertyDefns( );
		for ( Iterator iter = propDefns.iterator( ); iter.hasNext( ); )
		{
			PropertyDefn propDefn = (PropertyDefn) iter.next( );