Return empty Config fields, now omitempty, for API < 1.21

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

api/types/versions/v1p19/types.go

@@ -3,6 +3,7 @@ package v1p19
 
 import (
 	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/pkg/nat"
 	"github.com/docker/docker/runconfig"
 )
 
@@ -19,6 +20,10 @@ type ContainerJSON struct {
 type ContainerConfig struct {
 	*runconfig.Config
 
+	MacAddress      string
+	NetworkDisabled bool
+	ExposedPorts    map[nat.Port]struct{}
+
 	// backward compatibility, they now live in HostConfig
 	VolumeDriver string
 	Memory       int64

api/types/versions/v1p20/types.go

@@ -3,6 +3,7 @@ package v1p20
 
 import (
 	"github.com/docker/docker/api/types"
+	"github.com/docker/docker/pkg/nat"
 	"github.com/docker/docker/runconfig"
 )
 
@@ -17,6 +18,10 @@ type ContainerJSON struct {
 type ContainerConfig struct {
 	*runconfig.Config
 
+	MacAddress      string
+	NetworkDisabled bool
+	ExposedPorts    map[nat.Port]struct{}
+
 	// backward compatibility, they now live in HostConfig
 	VolumeDriver string
 }