[FAB-11976] hex encoding for binary keys in collection

Keys in a collection are hashed to binary and may contain unprintable
characters. This change set introduces hex encoding for said keys in order
to improve the usefulness of log entries.

Change-Id: I3bfcf63506cca968ca2d514c33bf5d20e4782e2a
Signed-off-by: Alessandro Sorniotti <ale.linux@sopit.net>
Signed-off-by: Matthias Neugschwandtner <eug@zurich.ibm.com>

core/common/validation/statebased/vpmanagerimpl.go

@@ -313,14 +313,14 @@ func (m *KeyLevelValidationParameterManagerImpl) GetValidationParameterForKey(cc
 	if coll == "" {
 		mdMap, err = state.GetStateMetadata(cc, key)
 		if err != nil {
-			err = errors.WithMessage(err, fmt.Sprintf("could not retrieve metadata for %s:%s:%s", cc, coll, key))
+			err = errors.WithMessage(err, fmt.Sprintf("could not retrieve metadata for %s:%s", cc, key))
 			logger.Errorf(err.Error())
 			return nil, err
 		}
 	} else {
 		mdMap, err = state.GetPrivateDataMetadata(cc, coll, key)
 		if err != nil {
-			err = errors.WithMessage(err, fmt.Sprintf("could not retrieve metadata for %s:%s:%s", cc, coll, key))
+			err = errors.WithMessage(err, fmt.Sprintf("could not retrieve metadata for %s:%s:%x", cc, coll, []byte(key)))
 			logger.Errorf(err.Error())
 			return nil, err
 		}