If someone go through this topic, I had to change next lines in Grongier.SQL.OutboundAdapter to make it work :

// FROMSet pHS=..%JGProxy.prepareStatement(..%ConnHandle,pSQLStatement)
// TOSet pHS=..%Connection.%JGProxy.prepareStatement(..%Connection.%ConnHandle,pSQLStatement)

// FROMset tResultCodes = ..%JGProxy.executeParametersBatch(pHS,.tArgs)
// TOset tResultCodes = ..%Connection.%JGProxy.executeParametersBatch(pHS,.tArgs)

// FROM set sc = .%JGProxy.removeStatement(pHS)
// TOset sc = ..%Connection.%JGProxy.removeStatement(pHS)

Hello @Oliver Wilms 

I'm strugguling with the exact same line. Did you find a solution? 

Thanks for your answer

Sorry, I didn't get back to you sooner but I tried both workaround and the first one worked for me

select cast(column_name as varchar(32767)) from table;

The second one didn't work in my case.

Thank you very much for your help.