Hi!

I encounterd some unexpected behaviour in the creation of keys, I'm using JabRef 3.8.2 on windows 10 10.0 amd64 Java 1.8.0_121.

Steps to reproduce:

1. In Preferences -> BibTeX key generator set the Default pattern field to [title][shorttitle]
2. Generate the key, for example for the document in the screenshot

Based on the documentation on http://help.jabref.org/en/BibtexKeyPatterns I was expecting the following output:
For [title]: HeuristicsandUsabilityGuidelinesfortheCreationandEvaluationofFuninVideogames
For [shorttitle]: Heuristicsandusability

Intead I got Heuristicsandusabilityguidelinesforthecreationandevaluationoffuninvideogames
and Heuristicsusabilityguidelines.

Put the excerpt of the log file here