Bug 213126 Add support for DataEngine-leve dataset cache
In many cases the DataEngine-leve dataset cache is useful which ensure that a dataset is executed one time during rendering one report. To support this feature a new dataset property should be added. The Birt customer can choose whether this dataset need to be cached or not by setting the property in deisgn time.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/parser/JointDataSetParseTest.java
* @throws DesignFileException
	 */
	public void testSemanticCheck( ) throws DesignFileException
	{
		openDesign( semanticCheckFileName );
		List errors = design.getErrorList( );
		assertEquals( 1, errors.size( ) );
		ErrorDetail error = (ErrorDetail) errors.get( 0 );
		assertEquals( SemanticError.DESIGN_EXCEPTION_INVALID_ELEMENT_REF, error
				.getErrorCode( ) );
		assertEquals( "JointDataSet", error.getElement( ).getName( ) ); 
	}
	/**
	 * Checks there is a semantic error. It is the value required exception with
	 * the given data set.
	 * 
	 * @param errors
	 *            the error list.
	 * @param dataSetName
	 *            the name of the data set.
	 */
	private void assertHasError( ErrorDetail errorDetail, String dataSetName )
	{
		assertTrue( PropertyValueException.DESIGN_EXCEPTION_VALUE_REQUIRED
				.equals( errorDetail.getErrorCode( ) )
				&& errorDetail.getElement( ) instanceof JointDataSet
				&& dataSetName.equals( errorDetail.getElement( ).getName( ) ) );
	}
}