izpack/izpack — pull request #230 by mtjandra (2014-07-10 14:21:37+00:00)
Title: [IZPACK-1131] - mustExist attribute for file fields

This is to address: https://jira.codehaus.org/browse/IZPACK-1131

Add a mustExist attribute for file fields, just like in dir fields.
If mustExist is not specified default is true.
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Also ensure not to print "null" during console installation when no label exists.