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
{
		List groups = this.baseQueryDefn.getGroups( );
		if ( groups != null && !groups.isEmpty( ) )
		{
			IQuery.GroupSpec[] groupSpecs = new IQuery.GroupSpec[groups.size( )];
			Iterator it = groups.iterator( );
			for ( int i = 0; it.hasNext( ); i++ )
			{
				IGroupDefinition src = (IGroupDefinition) it.next( );
				validateGroupExpression( src );
				String expr = getGroupKeyExpression( src );
				
				String groupName = populateGroupName( i, expr );
				
				IQuery.GroupSpec dest = QueryExecutorUtil.groupDefnToSpec( cx,
						src,
						expr,
						groupName,
						-1 );
				groupSpecs[i] = dest;
				this.temporaryComputedColumns.add( getComputedColumnInstance( cx,
						groupSpecs[i].getInterval( ),
						src,
						expr,
						groupName,
						dest ) );
			}
			odiQuery.setGrouping( Arrays.asList( groupSpecs ) );
		}
	}