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
cmd.setProperty( propDefn.getName( ), null );
							
							
							
							if ( definition != null && !definition.hasReferences( ) )
							{
								assert definition.getRoot( ) == module;
								ContentCommand contentCmd = new ContentCommand(
										module, module );
								contentCmd
										.remove(
												definition,
												ReportDesign.TEMPLATE_PARAMETER_DEFINITION_SLOT );
							}
						}
						catch ( SemanticException e )
						{
							assert false;
						}						
					}
				}
			}
			else if ( propDefn.getTypeCode( ) == PropertyType.LIST_TYPE
					&& propDefn.getSubTypeCode( ) == PropertyType.ELEMENT_REF_TYPE )
			{
				List valueList = (List) element.getLocalProperty( module,
						(ElementPropertyDefn) propDefn );
				if ( valueList != null )
				{
					for ( int i = valueList.size( ) - 1; i >= 0; i-- )