[FAB-12089] Add private metadata getter by hash

This change set adds GetPrivateDataMetadataByHash to the State
interface of validation plugins so that metadata for private keys
can be retrieved by the key hash.

Change-Id: I96f926a7d6ef142b1a7f58153aad55190ab4dfc5
Signed-off-by: Alessandro Sorniotti <ale.linux@sopit.net>
Signed-off-by: Matthias Neugschwandtner <eug@zurich.ibm.com>

core/common/validation/statebased/vpmanager_test.go

@@ -49,6 +49,10 @@ func (ms *mockState) GetPrivateDataMetadata(namespace, collection, key string) (
 	return ms.GetPrivateDataMetadataRv, ms.GetPrivateDataMetadataErr
 }
 
+func (ms *mockState) GetPrivateDataMetadataByHash(namespace, collection string, keyhash []byte) (map[string][]byte, error) {
+	return nil, nil
+}
+
 func (ms *mockState) Done() {
 	ms.DoneCalled = true
 }

core/handlers/validation/api/state/state.go

@@ -28,6 +28,9 @@ type State interface {
 	// GetPrivateDataMetadata gets the metadata of a private data item identified by a tuple <namespace, collection, key>
 	GetPrivateDataMetadata(namespace, collection, key string) (map[string][]byte, error)
 
+	// GetPrivateDataMetadataByHash gets the metadata of a private data item identified by a tuple <namespace, collection, keyhash>
+	GetPrivateDataMetadataByHash(namespace, collection string, keyhash []byte) (map[string][]byte, error)
+
 	// Done releases resources occupied by the State
 	Done()
 }