Bug 143173 No error for recursive including when exporting a report to a library
Steps to reproduce: 1.New a library named "Lib", add a lable in it 2.New a report, extends Lib.label 3.Export the report, choose target library "Lib" Expected result: Error to warn the recursive including Actual result: The target library includes itself without error
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/util/ModelUtil.java
return key1.compareTo( key2 );
			}
		} );
		return propDefns;
	}
	/**
	 * Sorts a list of element by their internal names.
	 * 
	 * @param elements
	 *            a list of <code>DesignElementHandle</code>
	 * @return a sorted list of element.
	 */
	public static List sortElementsByName( List elements )
	{
		List temp = new ArrayList( elements );
		Collections.sort( temp, new Comparator( ) {
			public int compare( Object o1, Object o2 )
			{
				DesignElementHandle handle1 = (DesignElementHandle) o1;
				DesignElementHandle handle2 = (DesignElementHandle) o2;
				String name1 = handle1.getName( );
				String name2 = handle2.getName( );
				if ( null == name1 )
				{
					if ( null == name2 )
						return 0;
					return -1;
				}