Bug 148747 Design become invalid when I extend a masterpage from Library
The attachment contains a report file and a library file. Reproduce: 1. Deploy the library("lib"), and open the report. 2. Drag Masterpage("page1") from "lib" to report. 3. Reopen the report, it become invalid.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/writer/ModuleWriter.java
* 
	 * @see org.eclipse.birt.report.model.elements.ElementVisitor#visitSimpleDataSet(org.eclipse.birt.report.model.elements.SimpleDataSet)
	 */
	public void visitDataSet( DataSet obj )
	{
		super.visitDataSet( obj );
		writeStructureList( obj, DataSet.PARAMETERS_PROP );
		writeStructureList( obj, DataSet.RESULT_SET_PROP );
		writeStructureList( obj, DataSet.RESULT_SET_HINTS_PROP );
		writeStructureList( obj, DataSet.COMPUTED_COLUMNS_PROP );
		writeStructureList( obj, DataSet.COLUMN_HINTS_PROP );
		writeStructureList( obj, DataSet.FILTER_PROP );
		
		CachedMetaData metadata = (CachedMetaData) obj.getLocalProperty(
				getModule( ), DataSet.CACHED_METADATA_PROP );
		if ( metadata != null )
		{
			
			writer.startElement( DesignSchemaConstants.STRUCTURE_TAG );
			writer.attribute( DesignElement.NAME_PROP,
					SimpleDataSet.CACHED_METADATA_PROP );
			writeStructureList( metadata, CachedMetaData.PARAMETERS_MEMBER );
			writeStructureList( metadata, CachedMetaData.RESULT_SET_MEMBER );
			writer.endElement( );
			
		}
	}
	/*
	 * (non-Javadoc)
	 *