Bug 201013 [Automation][Regression]Invalid group key column name: _{$TEMP_GROUP_1$} occurs when preview attached report[1102]
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
/**
	 * Validating the group expression.
	 * 
	 * @param src
	 * @throws DataException
	 */
	private void validateGroupExpression( IGroupDefinition src ) throws DataException
	{
		if ( ( src.getKeyColumn( ) == null || src.getKeyColumn( )
				.trim( )
				.length( ) == 0 )
				&& ( src.getKeyExpression( ) == null || src.getKeyExpression( )
						.trim( )
						.length( ) == 0 ) )
			throw new DataException( ResourceConstants.BAD_GROUP_EXPRESSION );
	}
	/**
	 * Populate the group name according to the given expression.
	 * 
	 * @param i
	 * @param expr
	 * @return
	 */
	private String populateGroupName( int i, String expr )
	{
		String groupName;
		if ( expr.trim( ).equalsIgnoreCase( "row[0]" )
				|| expr.trim( ).equalsIgnoreCase( "row._rowPosition" )
				|| expr.trim( ).equalsIgnoreCase( "dataSetRow[0]" )
				|| expr.trim( )