Avoid sending zero-value upstream defaults from api

agent/structs/config_entry.go

@@ -194,7 +194,9 @@ func (cfg *ConnectConfiguration) Normalize() {
 		v.Normalize()
 	}
 
-	cfg.UpstreamDefaults.Normalize()
+	if cfg.UpstreamDefaults != nil {
+		cfg.UpstreamDefaults.Normalize()
+	}
 }
 
 func (cfg ConnectConfiguration) Validate() error {
@@ -206,8 +208,11 @@ func (cfg ConnectConfiguration) Validate() error {
 		}
 	}
 
-	if err := cfg.UpstreamDefaults.Validate(); err != nil {
-		validationErr = multierror.Append(validationErr, fmt.Errorf("error in upstream defaults %v", err))
+	if cfg.UpstreamDefaults != nil {
+		err := cfg.UpstreamDefaults.Validate()
+		if err != nil {
+			validationErr = multierror.Append(validationErr, fmt.Errorf("error in upstream defaults %v", err))
+		}
 	}
 
 	return validationErr

api/config_entry.go

@@ -98,7 +98,7 @@ type ConnectConfiguration struct {
 	UpstreamConfigs map[string]UpstreamConfig `json:",omitempty" alias:"upstream_configs"`
 
 	// UpstreamDefaults contains default configuration for all upstreams of a given service
-	UpstreamDefaults UpstreamConfig `json:",omitempty" alias:"upstream_defaults"`
+	UpstreamDefaults *UpstreamConfig `json:",omitempty" alias:"upstream_defaults"`
 }
 
 type UpstreamConfig struct {

command/config/write/config_write_test.go

@@ -638,7 +638,7 @@ func TestParseConfigEntry(t *testing.T) {
 							},
 						},
 					},
-					UpstreamDefaults: api.UpstreamConfig{
+					UpstreamDefaults: &api.UpstreamConfig{
 						EnvoyClusterJSON:  "zip",
 						EnvoyListenerJSON: "zop",
 						Protocol:          "http",