JabRef version JabRef 5.1--2020-03-10--43f533b on Windows 10 10.0 amd64 Java 13.0.2

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

Steps to reproduce the behavior:

1. Add a file to General => File, which will add a file field looking like
   file = {:STAT/aa.pdf:PDF},
2. It will show an unrecognized file type icon in the linked files column instead of the pdf type icon (although it will open the pdf file using the proper reader)
3. Change it to file = {:STAT/aa.pdf:pdf},, the pdf type icon will be shown.