After saving draft of Content Type, you are not able to save any other changes if there is any field that has checkbox Required marked before saving.

Steps to reproduce a bug:

1. create new content type,
2. fill Name, Identifier and Content name pattern,
3. add new field (i tried with Authors, Rich text, Text line),
4. check "Require",
5. add new field or save draft
6. after that there's no possibility of changing Content type - adding one more field or trying to save result in error on the bottom of the screen:

   Failed to load 'http://localhost:8082/pjax/contenttype/update/55/eng-GB

I application log i can find this error:

[2017-10-19 14:24:35] request.CRITICAL: Uncaught PHP Exception eZ\Publish\API\Repository\Exceptions\PropertyNotFoundException: "Property 'field' not found on class 'EzSystems\RepositoryForms\Data\FieldDefinitionData'" at /Users/maciejtyrala/PhpstormProjects/ezplatform-ee-tutorial/vendor/ezsystems/ezpublish-kernel/eZ/Publish/API/Repository/Values/ValueObject.php line 101

Unknown macro: {"exception"}

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