PutDatabasRecord inserting NULL instead of an empty string

[#1]

I have a simple flow QueryDatabaseTableRecord >[CSV flowfile, Apache commons ] > PutDatabasRecord. The problem is that the last processor is trying to insert NULL instead of empty string as in source, which violates not null constraint. Is it possible to change this behaviour without adding additional processor? I want to keep it as simple as possible.

Thanks in advance.

Tomasz

[#2]

You can try modifying the Record Reader avro schema to something like this:

{"name": "xxx", "type": "string"], "default": ""}