diff --git a/pkg/apis/volumesnapshot/v1alpha1/types.go b/pkg/apis/volumesnapshot/v1alpha1/types.go
index 3461eb8a..9d91802f 100644
--- a/pkg/apis/volumesnapshot/v1alpha1/types.go
+++ b/pkg/apis/volumesnapshot/v1alpha1/types.go
@@ -81,8 +81,9 @@ type VolumeSnapshotSpec struct {
 	// +optional
 	VolumeSnapshotClassName string `json:"snapshotClassName" protobuf:"bytes,3,opt,name=snapshotClassName"`
 
-	// Size represents the size of the VolumeSnapshot
-	Size core_v1.ResourceList
+	// A description of the volume snapshot's resources and size.
+	// +optional
+	Size core_v1.ResourceList `json:"size,omitempty" protobuf:"bytes,4,rep,name=size,casttype=ResourceList,castkey=ResourceName"`
 }
 
 // VolumeSnapshotStatus is the status of the VolumeSnapshot
@@ -201,7 +202,7 @@ type VolumeSnapshotContentSpec struct {
 	// Name of the VolumeSnapshotClass used by the VolumeSnapshot. If not specified, a default snapshot class will
 	// be used if it is available.
 	// +optional
-	VolumeSnapshotClassName string `json:"snapshotClassName" protobuf:"bytes,3,opt,name=snapshotClassName"`
+	VolumeSnapshotClassName string `json:"snapshotClassName" protobuf:"bytes,4,opt,name=snapshotClassName"`
 }
 
 // VolumeSnapshotSource represents the actual location and type of the snapshot. Only one of its members may be specified.
@@ -214,22 +215,26 @@ type VolumeSnapshotSource struct {
 // Represents the source from CSI volume snapshot
 type CSIVolumeSnapshotSource struct {
 	// Driver is the name of the driver to use for this snapshot.
+	// This MUST be the same name returned by the CSI GetPluginName() call for
+	// that driver.
 	// Required.
-	Driver string `json:"driver"`
+	Driver string `json:"driver" protobuf:"bytes,1,opt,name=driver"`
 
 	// SnapshotHandle is the unique snapshot id returned by the CSI volume
 	// plugin’s CreateSnapshot to refer to the snapshot on all subsequent calls.
 	// Required.
-	SnapshotHandle string `json:"snapshotHandle"`
+	SnapshotHandle string `json:"snapshotHandle" protobuf:"bytes,2,opt,name=snapshotHandle"`
 
 	// Timestamp when the point-in-time snapshot is taken on the storage
 	// system. This timestamp will be generated by the CSI volume driver after
 	// the snapshot is cut. The format of this field should be a Unix nanoseconds
 	// time encoded as an int64. On Unix, the command `date +%s%N` returns
 	// the  current time in nanoseconds since 1970-01-01 00:00:00 UTC.
-	// This field is REQUIRED.
+	// This field is required in the CSI spec but optional here to support static binding.
+	// +optional
 	CreatedAt int64 `json:"createdAt,omitempty" protobuf:"varint,3,opt,name=createdAt"`
 
-	// Size represents the size of the VolumeSnapshot
-	Size core_v1.ResourceList
+	// A description of the volume snapshot's resources and size.
+	// +optional
+	Size core_v1.ResourceList `json:"size,omitempty" protobuf:"bytes,4,rep,name=size,casttype=ResourceList,castkey=ResourceName"`
 }