run golangci-lint and apply suggested fixes

rpc/grpcclientidentity/example/main.go

@@ -88,6 +88,9 @@ func server() {
 	log := logger.NewStderrDebugLogger()
 
 	srv, serve, err := grpchelper.NewServer(authListenerFactory, clientIdentityKey, log)
+	if err != nil {
+		onErr(err, "new server")
+	}
 	svc := &greeter{"hello "}
 	pdu.RegisterGreeterServer(srv, svc)
 

rpc/grpcclientidentity/example/pdu/grpcauth.pb.go

@@ -5,11 +5,10 @@ package pdu
 
 import (
 	fmt "fmt"
-	math "math"
-
 	proto "github.com/golang/protobuf/proto"
 	context "golang.org/x/net/context"
 	grpc "google.golang.org/grpc"
+	math "math"
 )
 
 // Reference imports to suppress errors if they are not otherwise used.