model: fix copypasta bug using JSON in Literal desirialization

Tests will appear in the next commit. I don't find it usefull
to add the tests here.

Author: filak-sap

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 - removed superfluous debug print when parsing FunctionImports from metadata - Jakub Filak
 - property 'Nullable' attributes are correctly parsed and respected - Vasilii Khomutov
+- use correct type of deserialization of Literal (URL) structure values - Jakub Filak
 
 ## [1.4.0]
 

pyodata/v2/model.py

@@ -562,7 +562,7 @@ def from_json(self, value):
         return EdmStructTypeSerializer.from_json(self._edm_type, value)
 
     def from_literal(self, value):
-        return EdmStructTypeSerializer.from_json(self._edm_type, value)
+        return EdmStructTypeSerializer.from_literal(self._edm_type, value)
 
 
 class EnumTypTrait(TypTraits):