Merge ~ack/maas:1929643-3.0 into maas:3.0

[Alberto Donato]

LP: #1929643 - only keep the JSON emitter for API responses

Currently JSON is the only supported output format for API calls

[Alberto Donato (ack)]

review: Approve

diff --git a/src/maasserver/api/support.py b/src/maasserver/api/support.py
index ba0729f..b2ed6df 100644
--- a/src/maasserver/api/support.py
+++ b/src/maasserver/api/support.py
@@ -53,8 +53,7 @@ class OperationsResource(Resource):
         return False
 
     def __call__(self, request, *args, **kwargs):
-        upcall = super().__call__
-        response = upcall(request, *args, **kwargs)
+        response = super().__call__(request, *args, **kwargs)
         response["X-MAAS-API-Hash"] = get_api_description_hash()
         return response
 
@@ -368,6 +367,12 @@ def method_fields_reserved_fields_patch(self, handler, fields):
 
 Emitter.method_fields = method_fields_reserved_fields_patch
 
+# only keep the JSON emitter as it's the only format we support
+for name in list(Emitter.EMITTERS):
+    if name == "json":
+        continue
+    Emitter.unregister(name)
+
 
 class ModelOperationsHandlerType(OperationsHandlerType, ABCMeta):
     """Metaclass for ModelOperationsHandler"""
diff --git a/src/maasserver/api/tests/test_support.py b/src/maasserver/api/tests/test_support.py
index 942d62e..fe8d411 100644
--- a/src/maasserver/api/tests/test_support.py
+++ b/src/maasserver/api/tests/test_support.py
@@ -17,6 +17,7 @@ from maasserver.api.doc import get_api_description_hash
 from maasserver.api.support import (
     admin_method,
     AdminRestrictedResource,
+    Emitter,
     OperationsHandlerMixin,
     OperationsResource,
     RestrictedResource,
@@ -28,6 +29,11 @@ from maasserver.testing.testcase import MAASServerTestCase
 from maastesting.testcase import MAASTestCase
 
 
+class TestEmitterOnlyJSON(MAASTestCase):
+    def test_emitters(self):
+        self.assertItemsEqual(Emitter.EMITTERS.keys(), ["json"])
+
+
 class StubHandler:
     """A stub handler class that breaks when called."""
 
diff --git a/src/maasserver/urls.py b/src/maasserver/urls.py
old mode 100755
new mode 100644