JIRA - XML-Export - escaped german letters

1. German special letters named "Umlaut" (e.g. 'ä') cause non well formed XML-Exportfiles.
I have opened such file with XML Spy which validates the XML structure and shows an error message (please see red circles at attached screenshot).

2. Escaped letters are exported with 'amp' (please see blue circles at attached screenshot).
For example(blanks used for better view): 'ä' is exported as '& a m p ; x E 4 ;' but normally it should be '& x E 4 ;'. Also by '& a m p ; q u o t ;' and '& a m p ; l t ;' ...
I plan to use the (unmodified) exported files to generate PDF files via XSL-FO. Now I have problems with the exported escape sequences.