chaining of modifiers does not work (in all cases?)

[lpirl]

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

JabRef version 4.1 on Debian buster/sid

Steps to reproduce:

1. chain modifiers for the BibTeX key generator as described in the docs
2. have a BibTex file where both modifiers would have an effect
3. observe that only the last modifier will be applied

Despite the configured pattern [auth:(_):lower][veryshorttitle:lower:(_)] , the example BibTex:

@Article{Interesting,
  title     = {The Interesting Title},
}

leads to the BibTex key as seen above.

Expected key (and BibTex, again):

@Article{_interesting,
  title     = {The Interesting Title},
}

Thanks for this powerful piece of FLOSS!

[lpirl]

Great. Thank you very much @tobiasdiez !