diff --git a/library/go/core/log/fields.go b/library/go/core/log/fields.go
index b30b46a5..f93e7cfc 100644
--- a/library/go/core/log/fields.go
+++ b/library/go/core/log/fields.go
@@ -49,6 +49,8 @@ const (
 	FieldTypeContext
 	// FieldTypeLazyCall wraps function to lazy evaluate it after log level confirm
 	FieldTypeLazyCall
+	// FieldTypeStringer is for fmt.Stringer
+	FieldTypeStringer
 
 	fieldTypeLast // service type for testing purposes
 )
@@ -166,6 +168,8 @@ func (f Field) Any() interface{} {
 		return f.Interface()
 	case FieldTypeLazyCall:
 		return f.Interface()
+	case FieldTypeStringer:
+		return f.Interface()
 	default:
 		// For when new field type is not added to this func
 		panic(fmt.Sprintf("unknown field type: %d", f.Type()))
@@ -182,6 +186,11 @@ func String(key, value string) Field {
 	return Field{key: key, ftype: FieldTypeString, string: value}
 }
 
+// Stringer constructs field from fmt.Stringer interface
+func Stringer(key string, value fmt.Stringer) Field {
+	return Field{key: key, ftype: FieldTypeStringer, iface: value}
+}
+
 // Sprintf constructs field of string type with formatting
 func Sprintf(key, format string, args ...interface{}) Field {
 	return Field{key: key, ftype: FieldTypeString, string: fmt.Sprintf(format, args...)}
diff --git a/library/go/core/log/zap/zapify.go b/library/go/core/log/zap/zapify.go
index d5d4b0ab..57ee93d8 100644
--- a/library/go/core/log/zap/zapify.go
+++ b/library/go/core/log/zap/zapify.go
@@ -80,6 +80,8 @@ func zapifyField(field log.Field) zap.Field {
 		return zap.Reflect(field.Key(), field.Interface())
 	case log.FieldTypeByteString:
 		return zap.ByteString(field.Key(), field.Binary())
+	case log.FieldTypeStringer:
+		return zap.Stringer(field.Key(), field.Interface().(fmt.Stringer))
 	case log.FieldTypeContext:
 		return Context(field.Interface().(context.Context))
 	case log.FieldTypeLazyCall:
diff --git a/transfer_manager/go/pkg/abstract/runtime.go b/transfer_manager/go/pkg/abstract/runtime.go
index 59f1f468..16ed679c 100644
--- a/transfer_manager/go/pkg/abstract/runtime.go
+++ b/transfer_manager/go/pkg/abstract/runtime.go
@@ -22,7 +22,6 @@ const (
 )
 
 type Runtime interface {
-	isRuntime()
 	NeedRestart(runtime Runtime) bool
 	WithDefaults()
 	Validate() error
@@ -47,6 +46,10 @@ func NewRuntime(runtime RuntimeType, runtimeSpec string) (Runtime, error) {
 	}
 }
 
+func RegisterRuntime(r RuntimeType, f func(spec string) (Runtime, error)) {
+	knownRuntimes[r] = f
+}
+
 // Parallelism params
 type ShardUploadParams struct {
 	JobCount     int //Workers count
@@ -65,7 +68,6 @@ func DefaultShardUploadParams() *ShardUploadParams {
 }
 
 type ShardingTaskRuntime interface {
-	isShardingEnabled()
 	WorkersNum() int
 	ThreadsNumPerWorker() int
 	CurrentJobIndex() int
diff --git a/transfer_manager/go/pkg/metering/metric.go b/transfer_manager/go/pkg/metering/metric.go
index 0d2d20e8..f44c8e89 100644
--- a/transfer_manager/go/pkg/metering/metric.go
+++ b/transfer_manager/go/pkg/metering/metric.go
@@ -37,7 +37,6 @@ type Metric interface {
 }
 
 type MetricState interface {
-	isMetricState()
 	Serialize(baseOpts *MeteringOpts) (map[MetricSchema][]string, error)
 }