Bug 182061 Data engine changes to support result set sharing
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/DataEngineImpl.java
if ( dataSources == null )
		{
			IllegalStateException e = new IllegalStateException( "DataEngine has been shutdown" );
			logger.logp( Level.WARNING,
					DataEngineImpl.class.getName( ),
					"defineDataSource",
					"DataEngine has been shutdown",
					e );
			throw e;
		}
		String name = dataSource.getName( );
		if ( name == null || name.length( ) == 0 )
		{
			IllegalArgumentException e=new IllegalArgumentException( "Data source has no name" );
			logger.logp( Level.WARNING,
					DataEngineImpl.class.getName( ),
					"defineDataSource",
					"Data source has no name",
					e );
			throw e; 
		}
		if ( logger.isLoggable( Level.FINE ) )
			logger.logp( Level.FINE,
					DataEngineImpl.class.getName( ),
					"defineDataSource",
					"DataEngine.defineDataSource: "
							+ LogUtil.toString( dataSource ) );
		
		
		Object existingDefn = dataSources.get( dataSource.getName( ) );