fix lint in exemplar

sdk/metric/internal/exemplar/value.go

@@ -28,7 +28,8 @@ type Value struct {
 func NewValue[N int64 | float64](value N) Value {
 	switch v := any(value).(type) {
 	case int64:
-		return Value{t: Int64ValueType, val: uint64(v)}
+		// This can be later converted back to int64 (overflow not checked).
+		return Value{t: Int64ValueType, val: uint64(v)} // nolint:gosec
 	case float64:
 		return Value{t: Float64ValueType, val: math.Float64bits(v)}
 	}

sdk/metric/internal/exemplar/value_test.go

@@ -10,8 +10,8 @@ import (
 )
 
 func TestValue(t *testing.T) {
-	const iVal, fVal = int64(43), float64(0.3)
-	i, f, bad := NewValue[int64](iVal), NewValue[float64](fVal), Value{}
+	const iVal, fVal, nVal = int64(43), float64(0.3), int64(-42)
+	i, f, n, bad := NewValue[int64](iVal), NewValue[float64](fVal), NewValue[int64](nVal), Value{}
 
 	assert.Equal(t, Int64ValueType, i.Type())
 	assert.Equal(t, iVal, i.Int64())
@@ -21,6 +21,10 @@ func TestValue(t *testing.T) {
 	assert.Equal(t, fVal, f.Float64())
 	assert.Equal(t, int64(0), f.Int64())
 
+	assert.Equal(t, Int64ValueType, n.Type())
+	assert.Equal(t, nVal, n.Int64())
+	assert.Equal(t, float64(0), i.Float64())
+
 	assert.Equal(t, UnknownValueType, bad.Type())
 	assert.Equal(t, float64(0), bad.Float64())
 	assert.Equal(t, int64(0), bad.Int64())