all: upgrade to google.golang.org/protobuf@v1.22.0 (#1114)

diff --git a/go.mod b/go.mod
index f17daa8..9c4c321 100644
--- a/go.mod
+++ b/go.mod
@@ -4,5 +4,5 @@
 
 require (
 	github.com/google/go-cmp v0.4.0
-	google.golang.org/protobuf v1.21.0
+	google.golang.org/protobuf v1.22.0
 )
diff --git a/go.sum b/go.sum
index 2c4d6c7..447f2ae 100644
--- a/go.sum
+++ b/go.sum
@@ -2,6 +2,7 @@
 github.com/golang/protobuf v1.4.0-rc.1.0.20200221234624-67d41d38c208/go.mod h1:xKAWHe0F5eneWXFV3EuXVDTCmh+JuBKY0li0aMyXATA=
 github.com/golang/protobuf v1.4.0-rc.2/go.mod h1:LlEzMj4AhA7rCAGe4KMBDvJI+AwstrUpVNzEA03Pprs=
 github.com/golang/protobuf v1.4.0-rc.4.0.20200313231945-b860323f09d0/go.mod h1:WU3c8KckQ9AFe+yFwt9sWVRKCVIyN9cPHBJSNnbL67w=
+github.com/golang/protobuf v1.4.0/go.mod h1:jodUvKwWbYaEsadDk5Fwe5c77LiNKVO9IDvqG2KuDX0=
 github.com/google/go-cmp v0.3.0/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMywk6iLU=
 github.com/google/go-cmp v0.4.0 h1:xsAVV57WRhGj6kEIi8ReJzQlHHqcBYCElAvkovg3B/4=
@@ -12,5 +13,6 @@
 google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
 google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQJ+fmap5saPgwCLgHXTUD7jkjRqWcaiX5VyM=
 google.golang.org/protobuf v1.20.1-0.20200309200217-e05f789c0967/go.mod h1:A+miEFZTKqfCUM6K7xSMQL9OKL/b6hQv+e19PK+JZNE=
-google.golang.org/protobuf v1.21.0 h1:qdOKuR/EIArgaWNjetjgTzgVTAZ+S/WXVrq9HW9zimw=
 google.golang.org/protobuf v1.21.0/go.mod h1:47Nbq4nVaFHyn7ilMalzfO3qCViNmqZ2kzikPIcrTAo=
+google.golang.org/protobuf v1.22.0 h1:cJv5/xdbk1NnMPR1VP9+HU6gupuG9MLBoH1r6RHZ2MY=
+google.golang.org/protobuf v1.22.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
diff --git a/protoc-gen-go/main.go b/protoc-gen-go/main.go
index 7515a18..d45b719 100644
--- a/protoc-gen-go/main.go
+++ b/protoc-gen-go/main.go
@@ -68,6 +68,7 @@
 				gengogrpc.GenerateFileContent(gen, f, g)
 			}
 		}
+		gen.SupportedFeatures = gengo.SupportedFeatures
 		return nil
 	})
 }
diff --git a/protoc-gen-go/plugin/plugin.pb.go b/protoc-gen-go/plugin/plugin.pb.go
index 2704536..b7b4a2f 100644
--- a/protoc-gen-go/plugin/plugin.pb.go
+++ b/protoc-gen-go/plugin/plugin.pb.go
@@ -12,6 +12,14 @@
 
 // Symbols defined in public import of google/protobuf/compiler/plugin.proto.
 
+type CodeGeneratorResponse_Feature = pluginpb.CodeGeneratorResponse_Feature
+
+const CodeGeneratorResponse_FEATURE_NONE = pluginpb.CodeGeneratorResponse_FEATURE_NONE
+const CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL = pluginpb.CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL
+
+var CodeGeneratorResponse_Feature_name = pluginpb.CodeGeneratorResponse_Feature_name
+var CodeGeneratorResponse_Feature_value = pluginpb.CodeGeneratorResponse_Feature_value
+
 type Version = pluginpb.Version
 type CodeGeneratorRequest = pluginpb.CodeGeneratorRequest
 type CodeGeneratorResponse = pluginpb.CodeGeneratorResponse