feat: add alias for details field in Rest Error (#928)

gapic-common/lib/gapic/rest/error.rb

@@ -14,6 +14,9 @@
 
 require "json"
 require "gapic/common/error"
+require "google/protobuf/well_known_types"
+# Not technically required but GRPC counterpart loads it and so should we for test parity
+require "google/rpc/error_details_pb"
 
 module Gapic
   module Rest
@@ -25,6 +28,8 @@ class Error < ::Gapic::Common::Error
       attr_reader :status
       # @return [Object, nil] the details as parsed from the response body
       attr_reader :details
+      # The Cloud error wrapper expect to see a `status_details` property
+      alias status_details details
       # @return [Object, nil] the headers of the REST error
       attr_reader :headers
       # The Cloud error wrapper expect to see a `header` property

gapic-common/test/gapic/rest/error_test.rb

@@ -95,6 +95,8 @@ def test_wrap_faraday
     refute_nil grpc_help
     assert_equal @help.links.first.description, grpc_help.links.first&.description
     assert_equal @help.links.first.url, grpc_help.links.first&.url
+
+    assert_equal gapic_err.details, gapic_err.status_details
   end
 
   # Tests that the message and the status code from within body