static identifier in docs

* OPTIONS response descritpion for workflow job template node identifier
value was an ever changing uuid4(). This is telling the user the wrong
thing. We can not know what uuid4() is going to be in the docs. Instead,
for the OPTIONS response description, tell the user the form that the
uuid4() takes, ie. xxx-xxxx...
* Note that the API browser still populates a uuid4 for the user when it
generates the sample POST data. This is nice.

awx/api/metadata.py

@@ -2,6 +2,7 @@
 # All Rights Reserved.
 
 from collections import OrderedDict
+from uuid import UUID
 
 # Django
 from django.core.exceptions import PermissionDenied
@@ -86,6 +87,8 @@ class Metadata(metadata.SimpleMetadata):
         # FIXME: Still isn't showing all default values?
         try:
             default = field.get_default()
+            if type(default) is UUID:
+                default = 'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx'
             if field.field_name == 'TOWER_URL_BASE' and default == 'https://towerhost':
                 default = '{}://{}'.format(self.request.scheme, self.request.get_host())
             field_info['default'] = default