Bug 138562 Splite extendsexcpetion to seperate sub class
The suggestion is Parent invalid Cycle extends Different type extends Not top level extends
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/elements/OdaDataSet.java
IExtendableElement,
			IOdaDataSetModel,
			IOdaExtendableElementModel
{
	/**
	 * Extensibility provider which provides the extension logic.
	 */
	private ODAProvider provider = null;
	/**
	 * ID of the extension which extends this ODA data set
	 */
	protected String extensionID = null;
	/**
	 * Default constructor.
	 */
	public OdaDataSet( )
	{
		super( );
	}
	/**
	 * Constructs an extended data set with name.
	 * 
	 * @param theName
	 *            the name of this extended data set
	 */
	public OdaDataSet( String theName )
	{
		super( theName );
	}
	/*