Bug 199021 Error message pops up several times when click an invalid dataset
Description: There is a sqlserver datasource and dataset, remove the jtds driver to let the dataset invalid. Double click on the dataset, the error message will pop up serveral times. Build version:2.2.0.v20070807-0630 Steps to reproduce: 1. Create a sqlserver datasource and dataset. 2. Remove the jtds driver, and the dataset will be invalid. 3. Double click on the dataset. Expect result: Error message pops up once to indicate the problem. Actual result: Error message pops up serveral times.
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/provider/JdbcMetaDataProvider.java
.getValue( );
		String driver = (String) handle.getPublicProperties( )
				.findProperty( Constants.ODADriverClass )
				.getValue( );
		
		jdbcConnection = connect( userName,
				passWord,
				url,
				driver,
				handle.getOdaExtensionId( ) ); 
		
		return jdbcConnection;
	}
	
	/*
	 *  (non-Javadoc)
	 * @see org.eclipse.birt.report.data.oda.jdbc.ui.provider.IMetadataProvider#getConnection()
	 */
	public Connection getConnection( )
	{
		return jdbcConnection;
	}
	
	/*
	 *  (non-Javadoc)
	 * @see org.eclipse.birt.report.data.oda.jdbc.ui.provider.IMetadataProvider#closeConnection()
	 */
	public void closeConnection()
	{
		if ( jdbcConnection != null )