remove Set method for cumulatives. (#1120)

diff --git a/metric/cumulative.go b/metric/cumulative.go
index 6d3be3f..549d091 100644
--- a/metric/cumulative.go
+++ b/metric/cumulative.go
@@ -59,25 +59,6 @@
 	return entry.(*Float64CumulativeEntry), nil
 }
 
-// Set sets the cumulative entry value to provided val. It returns without updating if the value is
-// negative or lower than previously stored value.
-func (e *Float64CumulativeEntry) Set(val float64) {
-	var swapped, equalOrLess bool
-	if val <= 0.0 {
-		return
-	}
-	for !swapped && !equalOrLess {
-		oldBits := atomic.LoadUint64(&e.val)
-		oldVal := math.Float64frombits(oldBits)
-		if val > oldVal {
-			valBits := math.Float64bits(val)
-			swapped = atomic.CompareAndSwapUint64(&e.val, oldBits, valBits)
-		} else {
-			equalOrLess = true
-		}
-	}
-}
-
 // Inc increments the cumulative entry value by val. It returns without incrementing if the val
 // is negative.
 func (e *Float64CumulativeEntry) Inc(val float64) {
@@ -129,23 +110,6 @@
 	return entry.(*Int64CumulativeEntry), nil
 }
 
-// Set sets the value of the cumulative entry to the provided value. It returns without updating
-// if the val is negative or if the val is lower than previously stored value.
-func (e *Int64CumulativeEntry) Set(val int64) {
-	var swapped, equalOrLess bool
-	if val <= 0 {
-		return
-	}
-	for !swapped && !equalOrLess {
-		old := atomic.LoadInt64(&e.val)
-		if val > old {
-			swapped = atomic.CompareAndSwapInt64(&e.val, old, val)
-		} else {
-			equalOrLess = true
-		}
-	}
-}
-
 // Inc increments the current cumulative entry value by val. It returns without incrementing if
 // the val is negative.
 func (e *Int64CumulativeEntry) Inc(val int64) {
diff --git a/metric/cumulative_test.go b/metric/cumulative_test.go
index 538320c..6b2110d 100644
--- a/metric/cumulative_test.go
+++ b/metric/cumulative_test.go
@@ -28,7 +28,7 @@
 	f, _ := r.AddFloat64Cumulative("TestCumulative",
 		WithLabelKeys("k1", "k2"))
 	e, _ := f.GetEntry(metricdata.LabelValue{}, metricdata.LabelValue{})
-	e.Set(5)
+	e.Inc(5)
 	e, _ = f.GetEntry(metricdata.NewLabelValue("k1v1"), metricdata.LabelValue{})
 	e.Inc(1)
 	e, _ = f.GetEntry(metricdata.NewLabelValue("k1v1"), metricdata.LabelValue{})
@@ -103,7 +103,7 @@
 	}
 }
 
-func TestInt64CumulativeEntry_IncAndSet(t *testing.T) {
+func TestInt64CumulativeEntry_IncNegative(t *testing.T) {
 	r := NewRegistry()
 	g, _ := r.AddInt64Cumulative("bm")
 	e, _ := g.GetEntry()
@@ -111,12 +111,6 @@
 	readAndCompareInt64Val("inc", r, 5, t)
 	e.Inc(-2)
 	readAndCompareInt64Val("inc negative", r, 5, t)
-	e.Set(-2)
-	readAndCompareInt64Val("set negative", r, 5, t)
-	e.Set(4)
-	readAndCompareInt64Val("set lower", r, 5, t)
-	e.Set(9)
-	readAndCompareInt64Val("set higher", r, 9, t)
 }
 
 func readAndCompareFloat64Val(testname string, r *Registry, want float64, t *testing.T) {
@@ -126,7 +120,7 @@
 	}
 }
 
-func TestFloat64CumulativeEntry_IncAndSet(t *testing.T) {
+func TestFloat64CumulativeEntry_IncNegative(t *testing.T) {
 	r := NewRegistry()
 	g, _ := r.AddFloat64Cumulative("bm")
 	e, _ := g.GetEntry()
@@ -134,12 +128,6 @@
 	readAndCompareFloat64Val("inc", r, 5.0, t)
 	e.Inc(-2.0)
 	readAndCompareFloat64Val("inc negative", r, 5.0, t)
-	e.Set(-2.0)
-	readAndCompareFloat64Val("set negative", r, 5.0, t)
-	e.Set(4.0)
-	readAndCompareFloat64Val("set lower", r, 5.0, t)
-	e.Set(9.9)
-	readAndCompareFloat64Val("set higher", r, 9.9, t)
 }
 
 func TestCumulativeWithSameNameDiffType(t *testing.T) {