Empty fields omitted in JSON conversion

This is a complex question about a complex problem, but please feel free to read i anyway :-)

We use NXLog to read the Windows eventlog and also csv files. We send the data to a linux loghost which does some regexp-based parsing.

We now encounter problems with missing fields.

Example 1: A csv file with three columns A, B and C. It looks like this:

AskedAugust 15, 2018 - 5:21pm