Updated the expected status code for unimplemented api errors. (#4802)

* Updated the expected status code for unimplemented api errors.

api/apierror.go

@@ -15,7 +15,9 @@ var (
 	ErrInvalidArgument  = &Error{Kind: codes.InvalidArgument.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusBadRequest}}}
 	ErrPermissionDenied = &Error{Kind: codes.PermissionDenied.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusForbidden}}}
 	ErrUnauthorized     = &Error{Kind: codes.Unauthenticated.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusUnauthorized}}}
-	ErrUnimplemented    = &Error{Kind: codes.Unimplemented.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusNotImplemented}}}
+	// internal/daemon/controller/handlers/errors.go detects status.Code(inErr) == codes.Unimplemented
+	// and sets http status http.StatusMethodNotAllowed
+	ErrUnimplemented    = &Error{Kind: codes.Unimplemented.String(), response: &Response{resp: &http.Response{StatusCode: http.StatusMethodNotAllowed}}}
 	ErrInvalidListToken = &Error{Kind: "invalid list token", response: &Response{resp: &http.Response{StatusCode: http.StatusBadRequest}}}
 )