Avoid generating singleton Unions

Author: nkrishnaswami

end_to_end_tests/multiple-media-types-golden-record/multiple_media_types_client/api/multiple_media_types/post.py

@@ -33,6 +33,11 @@ def _parse_response(
         if response.headers.get("content-type") == "application/octet-stream":
             response_200 = cast(Any, response.content)
             return response_200
+    if response.status_code == 404:
+        response_404: Any
+        if response.headers.get("content-type") == "text/plain":
+            response_404 = cast(Any, response.text)
+            return response_404
     if response.status_code == 503:
         response_503: Union[ErrorResponse, Any]
         if response.headers.get("content-type") == "application/json":

end_to_end_tests/multiple-media-types.yml

@@ -15,6 +15,10 @@ paths:
               schema:
                 const: "Why have a fixed response? I dunno"
             "application/octet-stream": {}
+        "404":
+          description: "Not Found"
+          content:
+            "text/plain": {}
         "503":
           description: "Server Not Available"
           content:

openapi_python_client/templates/endpoint_module.py.jinja

@@ -82,7 +82,11 @@ def _parse_response(*, client: Union[AuthenticatedClient, Client], response: htt
         return None
         {% endif %}
     {% else %}
+        {% if response.content[1:] %}
         {{response.content[0].prop.python_name}}: Union[{{ response.content | map(attribute='prop') | map(attribute='type_string')  | join(', ') }}]
+        {% else %}
+        {{response.content[0].prop.python_name}}: {{response.content[0].prop.type_string}}
+        {% endif %}
         {% for media_type in response.content %}
         {% if media_type.content_type %}
         if response.headers.get("content-type") == "{{ media_type.content_type }}":