Bug 196745 Data Engine implementation of BPS80- Result Set Sharing
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/ResultIterator.java
*/
	private void validateManualBindingExpressions( Map exprs )
			throws DataException
	{
		Set validDataSetColumnNames = populateValidDataSetColumnNameSet( ); 
		Iterator it = exprs.keySet().iterator();
		while( it.hasNext() )
		{
			Object key = it.next();
			IBaseExpression expr =  ((IBinding)exprs.get(key)).getExpression( );
			List usedDataSetExprs = ExpressionCompilerUtil.extractDataSetColumnExpression( expr );
			for ( int j = 0; j < usedDataSetExprs.size( ); j++ )
			{
				if ( !( validDataSetColumnNames.contains( usedDataSetExprs.get( j ) ) || usedDataSetExprs.get( j )
						.equals( "_rowPosition" ) ) )
					throw new DataException( ResourceConstants.COLUMN_BINDING_REFER_TO_INEXIST_COLUMN,
							new Object[]{
									key,
									usedDataSetExprs.get( j )
							} );
			}
		}
	}
	/**
	 * Populate all valid data set column names and alias.
	 * 
	 * @return
	 * @throws DataException
	 */
	private Set populateValidDataSetColumnNameSet( ) throws DataException