Bug 197228 Need updaet createdBy info when serialize the module
When open module, designer will pass the property map which contains the createdBy info. this info should be retained by moduleHandle and then be updated and written when doing serialization. Note if this info is null, model should not update it during serialization. This could happen for api users or third-party designer. For BIRT designer, it will guarantee this value always not null.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
*            the name of the data source to find.
	 * @return the data source, or null if the data source is not found.
	 */
	public DesignElement findDataSource( String name )
	{
		return resolveElement( name, null, MetaDataDictionary.getInstance( )
				.getElement( ReportDesignConstants.DATA_SOURCE_ELEMENT ) );
	}
	/**
	 * Finds a data set by name in this module and the included modules.
	 * 
	 * @param name
	 *            the name of the data set to find.
	 * @return the data set, or null if the data set is not found.
	 */
	public DesignElement findDataSet( String name )
	{
		return resolveElement( name, null, MetaDataDictionary.getInstance( )
				.getElement( ReportDesignConstants.DATA_SET_ELEMENT ) );
	}
	/**
	 * Finds a master page by name in this module and the included modules.
	 * 
	 * @param name
	 *            the master page name.
	 * @return the master page, if found, otherwise null.
	 */
	public DesignElement findPage( String name )
	{
		return resolveNativeElement( name, PAGE_NAME_SPACE );