ERP5Form/hal_json: support disabled items in ParallelListField

(Multi)ListField renders items with None as value as disabled option, but this
was not really supported in ParallelListField because ParallelListField treated
the same way the empty ('', '') item and a disabled item ("Disabled", None).

Adjust the conditions to differentiate the two cases.

bt5/erp5_hal_json_style/SkinTemplateItem/portal_skins/erp5_hal_json_style/ERP5Document_getHateoas.py

@@ -480,7 +480,7 @@ def renderField(traversed_document, field, form, value=MARKER, meta_type=None, k
         # Copy the dict, as some hashscript cache the result,
         # which should not in this case be modified
         result.update({"subfield_list": [x.copy() for x in getattr(field, hash_script_id)(
-                [x for x in result['items'] if (x[1] and x[0])],
+                [x for x in result['items'] if (x[1] != '' and x[0] != '')],
                 # Drop empty values
                 result['default'],
                 default_sub_field_property_dict={

product/ERP5Form/ParallelListField.py

@@ -229,7 +229,7 @@ class ParallelListField(ZMIField):
 
 def generateSubForm(self, value, REQUEST):
   item_list = [x for x in self.get_value('items', REQUEST=REQUEST)
-                 if x[0] != '' and x[1]]
+                 if x[0] != '' and x[1] != '']
 
   value_list = value
   if not isinstance(value_list, (list, tuple)):