The end result of this bug is that no issue types are shown in the issue type dropdown on the create issue page. The page contains some javascript that hides/displayes issue types depending on which project is selected. The page contains issue types for all the different issue type schemes grouped in option groups and further grouped by a className attribute that is set to the fieldconfigurationscheme id:

<select name="issuetype" id="issuetype" class="imagebacked">
 <optgroup label="DATEX Online"> 
     <option id="issuetype10071" class="10071" value="" style="background-image: url(/jira/images/icons/information.gif);" >Please select...</option>
     <option id="issuetype100711" class="10071" value="1" style="background-image: url(/jira/images/icons/bug.gif);" selected="selected" >Bug</option>
...
</optgroup> 
<optgroup label="Default scheme (unlisted projects)"> 
     <option id="issuetype100521" class="10052" value="1" style="background-image: url(/jira/images/icons/bug.gif);"231 selected="selected" >Bug</option>
     <option id="issuetype100522" class="10052" value="2" style="background-image: url(/jira/images/icons/newfeature.gif);"233 >New Feature</option>
...

However, the javascript function that gets called to decide if a certain group of issue types needs to be displayed relies on a mapping of project ids -> field configuration ids:

addEntry('10000','10091');
addEntry('10021','10072');
...

The problem is that the fieldconfigurationscheme id and the related fieldconfiguration id are not necessarily the same, as they are related via the fieldconfigschemeissuetype many to many table in the database.

We need to make sure that the javascript can handle the case, where the ids differ.