diff --git a/go/src/v.io/x/sensorlog/internal/sbmodel/types.vdl.go b/go/src/v.io/x/sensorlog/internal/sbmodel/types.vdl.go
index 6abdceb..ed58db1 100644
--- a/go/src/v.io/x/sensorlog/internal/sbmodel/types.vdl.go
+++ b/go/src/v.io/x/sensorlog/internal/sbmodel/types.vdl.go
@@ -46,34 +46,28 @@
 		return err
 	}
 
-	var2 := (m.Desc == "")
-	if !var2 {
-		keyTarget3, fieldTarget4, err := fieldsTarget1.StartField("Desc")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget2, fieldTarget3, err := fieldsTarget1.StartField("Desc")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget3.FromString(string(m.Desc), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget4.FromString(string(m.Desc), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget3, fieldTarget4); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget2, fieldTarget3); err != nil {
+			return err
 		}
 	}
-	var5 := (m.SgPublishSb == "")
-	if !var5 {
-		keyTarget6, fieldTarget7, err := fieldsTarget1.StartField("SgPublishSb")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget4, fieldTarget5, err := fieldsTarget1.StartField("SgPublishSb")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget5.FromString(string(m.SgPublishSb), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget7.FromString(string(m.SgPublishSb), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget6, fieldTarget7); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget4, fieldTarget5); err != nil {
+			return err
 		}
 	}
 	if err := t.FinishFields(fieldsTarget1); err != nil {
@@ -86,12 +80,6 @@
 	return nil
 }
 
-func (m *VDeviceCfg) IsZero() bool {
-
-	var1 := (*m == VDeviceCfg{})
-	return var1
-}
-
 type KDeviceCfg struct {
 	DevId string
 }
@@ -111,19 +99,16 @@
 		return err
 	}
 
-	var2 := (m.DevId == "")
-	if !var2 {
-		keyTarget3, fieldTarget4, err := fieldsTarget1.StartField("DevId")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget2, fieldTarget3, err := fieldsTarget1.StartField("DevId")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget3.FromString(string(m.DevId), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget4.FromString(string(m.DevId), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget3, fieldTarget4); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget2, fieldTarget3); err != nil {
+			return err
 		}
 	}
 	if err := t.FinishFields(fieldsTarget1); err != nil {
@@ -136,12 +121,6 @@
 	return nil
 }
 
-func (m *KDeviceCfg) IsZero() bool {
-
-	var1 := (*m == KDeviceCfg{})
-	return var1
-}
-
 // streamdef : <DevId>/<StreamId>
 // Configures a stream of data to be measured.
 type VStreamDef struct {
@@ -166,50 +145,41 @@
 		return err
 	}
 
-	var2 := (m.Desc == "")
-	if !var2 {
-		keyTarget3, fieldTarget4, err := fieldsTarget1.StartField("Desc")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget2, fieldTarget3, err := fieldsTarget1.StartField("Desc")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget3.FromString(string(m.Desc), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget4.FromString(string(m.Desc), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget3, fieldTarget4); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget2, fieldTarget3); err != nil {
+			return err
 		}
 	}
-	var5 := m.Sampler.IsZero()
-	if !var5 {
-		keyTarget6, fieldTarget7, err := fieldsTarget1.StartField("Sampler")
-		if err != vdl.ErrFieldNoExist && err != nil {
-			return err
-		}
-		if err != vdl.ErrFieldNoExist {
+	keyTarget4, fieldTarget5, err := fieldsTarget1.StartField("Sampler")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
 
-			if err := m.Sampler.FillVDLTarget(fieldTarget7, __VDLType_types_v_io_x_sensorlog_internal_sbmodel_SamplerDef); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget6, fieldTarget7); err != nil {
-				return err
-			}
-		}
-	}
-	var8 := (m.Enabled == false)
-	if !var8 {
-		keyTarget9, fieldTarget10, err := fieldsTarget1.StartField("Enabled")
-		if err != vdl.ErrFieldNoExist && err != nil {
+		if err := m.Sampler.FillVDLTarget(fieldTarget5, __VDLType_types_v_io_x_sensorlog_internal_sbmodel_SamplerDef); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget10.FromBool(bool(m.Enabled), vdl.BoolType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget9, fieldTarget10); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget4, fieldTarget5); err != nil {
+			return err
+		}
+	}
+	keyTarget6, fieldTarget7, err := fieldsTarget1.StartField("Enabled")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget7.FromBool(bool(m.Enabled), vdl.BoolType); err != nil {
+			return err
+		}
+		if err := fieldsTarget1.FinishField(keyTarget6, fieldTarget7); err != nil {
+			return err
 		}
 	}
 	if err := t.FinishFields(fieldsTarget1); err != nil {
@@ -222,12 +192,6 @@
 	return nil
 }
 
-func (m *VStreamDef) IsZero() bool {
-
-	var1 := (*m == VStreamDef{})
-	return var1
-}
-
 type KStreamDef struct {
 	DevId    string
 	StreamId string
@@ -248,34 +212,28 @@
 		return err
 	}
 
-	var2 := (m.DevId == "")
-	if !var2 {
-		keyTarget3, fieldTarget4, err := fieldsTarget1.StartField("DevId")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget2, fieldTarget3, err := fieldsTarget1.StartField("DevId")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget3.FromString(string(m.DevId), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget4.FromString(string(m.DevId), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget3, fieldTarget4); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget2, fieldTarget3); err != nil {
+			return err
 		}
 	}
-	var5 := (m.StreamId == "")
-	if !var5 {
-		keyTarget6, fieldTarget7, err := fieldsTarget1.StartField("StreamId")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget4, fieldTarget5, err := fieldsTarget1.StartField("StreamId")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget5.FromString(string(m.StreamId), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget7.FromString(string(m.StreamId), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget6, fieldTarget7); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget4, fieldTarget5); err != nil {
+			return err
 		}
 	}
 	if err := t.FinishFields(fieldsTarget1); err != nil {
@@ -288,12 +246,6 @@
 	return nil
 }
 
-func (m *KStreamDef) IsZero() bool {
-
-	var1 := (*m == KStreamDef{})
-	return var1
-}
-
 // Sampling script and polling frequency.
 type SamplerDef struct {
 	// Shell script executed after every Interval, starting from Start.
@@ -317,61 +269,52 @@
 		return err
 	}
 
-	var2 := (m.Script == "")
-	if !var2 {
-		keyTarget3, fieldTarget4, err := fieldsTarget1.StartField("Script")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget2, fieldTarget3, err := fieldsTarget1.StartField("Script")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget3.FromString(string(m.Script), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget4.FromString(string(m.Script), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget3, fieldTarget4); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget2, fieldTarget3); err != nil {
+			return err
 		}
 	}
-	var wireValue5 time_2.Time
-	if err := time_2.TimeFromNative(&wireValue5, m.Start); err != nil {
+	var wireValue4 time_2.Time
+	if err := time_2.TimeFromNative(&wireValue4, m.Start); err != nil {
 		return err
 	}
 
-	var6 := wireValue5.IsZero()
-	if !var6 {
-		keyTarget7, fieldTarget8, err := fieldsTarget1.StartField("Start")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget5, fieldTarget6, err := fieldsTarget1.StartField("Start")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+
+		if err := wireValue4.FillVDLTarget(fieldTarget6, __VDLType_types_time_Time); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-
-			if err := wireValue5.FillVDLTarget(fieldTarget8, __VDLType_types_time_Time); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget7, fieldTarget8); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget5, fieldTarget6); err != nil {
+			return err
 		}
 	}
-	var wireValue9 time_2.Duration
-	if err := time_2.DurationFromNative(&wireValue9, m.Interval); err != nil {
+	var wireValue7 time_2.Duration
+	if err := time_2.DurationFromNative(&wireValue7, m.Interval); err != nil {
 		return err
 	}
 
-	var10 := wireValue9.IsZero()
-	if !var10 {
-		keyTarget11, fieldTarget12, err := fieldsTarget1.StartField("Interval")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget8, fieldTarget9, err := fieldsTarget1.StartField("Interval")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+
+		if err := wireValue7.FillVDLTarget(fieldTarget9, __VDLType_types_time_Duration); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-
-			if err := wireValue9.FillVDLTarget(fieldTarget12, __VDLType_types_time_Duration); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget11, fieldTarget12); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget8, fieldTarget9); err != nil {
+			return err
 		}
 	}
 	if err := t.FinishFields(fieldsTarget1); err != nil {
@@ -384,12 +327,6 @@
 	return nil
 }
 
-func (m *SamplerDef) IsZero() bool {
-
-	var1 := (*m == SamplerDef{})
-	return var1
-}
-
 // sdata : <DevId>/<StreamId>/<Timestamp>
 // Measured data value or error.
 type KDataPoint struct {
@@ -411,55 +348,46 @@
 		return err
 	}
 
-	var2 := (m.DevId == "")
-	if !var2 {
-		keyTarget3, fieldTarget4, err := fieldsTarget1.StartField("DevId")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget2, fieldTarget3, err := fieldsTarget1.StartField("DevId")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget3.FromString(string(m.DevId), vdl.StringType); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget4.FromString(string(m.DevId), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget3, fieldTarget4); err != nil {
-				return err
-			}
-		}
-	}
-	var5 := (m.StreamId == "")
-	if !var5 {
-		keyTarget6, fieldTarget7, err := fieldsTarget1.StartField("StreamId")
-		if err != vdl.ErrFieldNoExist && err != nil {
+		if err := fieldsTarget1.FinishField(keyTarget2, fieldTarget3); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-			if err := fieldTarget7.FromString(string(m.StreamId), vdl.StringType); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget6, fieldTarget7); err != nil {
-				return err
-			}
+	}
+	keyTarget4, fieldTarget5, err := fieldsTarget1.StartField("StreamId")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+		if err := fieldTarget5.FromString(string(m.StreamId), vdl.StringType); err != nil {
+			return err
+		}
+		if err := fieldsTarget1.FinishField(keyTarget4, fieldTarget5); err != nil {
+			return err
 		}
 	}
-	var wireValue8 time_2.Time
-	if err := time_2.TimeFromNative(&wireValue8, m.Timestamp); err != nil {
+	var wireValue6 time_2.Time
+	if err := time_2.TimeFromNative(&wireValue6, m.Timestamp); err != nil {
 		return err
 	}
 
-	var9 := wireValue8.IsZero()
-	if !var9 {
-		keyTarget10, fieldTarget11, err := fieldsTarget1.StartField("Timestamp")
-		if err != vdl.ErrFieldNoExist && err != nil {
+	keyTarget7, fieldTarget8, err := fieldsTarget1.StartField("Timestamp")
+	if err != vdl.ErrFieldNoExist && err != nil {
+		return err
+	}
+	if err != vdl.ErrFieldNoExist {
+
+		if err := wireValue6.FillVDLTarget(fieldTarget8, __VDLType_types_time_Time); err != nil {
 			return err
 		}
-		if err != vdl.ErrFieldNoExist {
-
-			if err := wireValue8.FillVDLTarget(fieldTarget11, __VDLType_types_time_Time); err != nil {
-				return err
-			}
-			if err := fieldsTarget1.FinishField(keyTarget10, fieldTarget11); err != nil {
-				return err
-			}
+		if err := fieldsTarget1.FinishField(keyTarget7, fieldTarget8); err != nil {
+			return err
 		}
 	}
 	if err := t.FinishFields(fieldsTarget1); err != nil {
@@ -472,12 +400,6 @@
 	return nil
 }
 
-func (m *KDataPoint) IsZero() bool {
-
-	var1 := (*m == KDataPoint{})
-	return var1
-}
-
 type (
 	// VDataPoint represents any single field of the VDataPoint union type.
 	VDataPoint interface {
@@ -490,7 +412,6 @@
 		// __VDLReflect describes the VDataPoint union type.
 		__VDLReflect(__VDataPointReflect)
 		FillVDLTarget(vdl.Target, *vdl.Type) error
-		IsZero() bool
 	}
 	// VDataPointValue represents field Value of the VDataPoint union type.
 	VDataPointValue struct{ Value float64 }
@@ -539,12 +460,6 @@
 	return nil
 }
 
-func (m VDataPointValue) IsZero() bool {
-
-	var2 := (m.Value == float64(0))
-	return var2
-}
-
 func (x VDataPointError) Index() int                       { return 1 }
 func (x VDataPointError) Interface() interface{}           { return x.Value }
 func (x VDataPointError) Name() string                     { return "Error" }
@@ -577,12 +492,6 @@
 	return nil
 }
 
-func (m VDataPointError) IsZero() bool {
-
-	unionField2 := false
-	return unionField2
-}
-
 func init() {
 	vdl.Register((*VDeviceCfg)(nil))
 	vdl.Register((*KDeviceCfg)(nil))