chore(binding): improved Body.Close

Change-Id: I7973ed3f7a2e47f6aa91575272e387bb7df87c6c

Author: andeya

binding/body.go

@@ -38,7 +38,11 @@ type Body struct {
 }
 
 // Close close.
-func (Body) Close() error { return nil }
+func (b *Body) Close() error {
+	b.Buffer = nil
+	b.bodyBytes = nil
+	return nil
+}
 
 // Reset zero offset.
 func (b *Body) Reset() {

binding/body_test.go

@@ -40,4 +40,6 @@ func TestBody(t *testing.T) {
 	b, err = ioutil.ReadAll(body)
 	assert.NoError(t, err)
 	assert.Equal(t, []byte("abc"), b)
+	body.Close()
+	assert.Equal(t, []byte(nil), body.Bytes())
 }