many fixes

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

client/client.go

@@ -11,7 +11,8 @@ import (
 
 var (
 	// DefaultClient is the global default client
-	DefaultClient Client = NewClient()
+	DefaultClient      Client = NewClient()
+	DefaultContentType        = "application/json"
 )
 
 // Client is the interface used to make requests to services.

client/noop.go

@@ -20,10 +20,6 @@ var (
 	}
 )
 
-const (
-	defaultContentType = "application/json"
-)
-
 type noopClient struct {
 	opts Options
 }

client/options.go

@@ -151,7 +151,7 @@ type RequestOptions struct {
 func NewOptions(opts ...Option) Options {
 	options := Options{
 		Context:     context.Background(),
-		ContentType: "application/json",
+		ContentType: DefaultContentType,
 		Codecs:      make(map[string]codec.Codec),
 		CallOptions: CallOptions{
 			Backoff:        DefaultBackoff,