fix annotate to json with empty comment

parser/annotator.go

@@ -57,7 +57,13 @@ func (a *Annotator) Annotate(comment string) []map[string]interface{} {
 
 //parse annotation to json
 func (a *Annotator) AnnotateToJson(comment string) (string, error) {
+	if comment == "" {
+		return "", nil
+	}
 	annotate := a.Annotate(comment)
+	if len(annotate) == 0 {
+		return "", nil
+	}
 	result, err := json.MarshalIndent(annotate, "", "  ")
 	return string(result), err
 }

parser/annotator_test.go

@@ -50,7 +50,7 @@ func TestAnnotate(t *testing.T) {
 }
 
 func TestAnnotateToJson(t *testing.T) {
-	expect := `[
+	expect1 := `[
   {
     "Name": [
       "Field1"
@@ -69,9 +69,11 @@ func TestAnnotateToJson(t *testing.T) {
   }
 ]`
 
-	actual, _ := BeeAnnotator.AnnotateToJson(Annotation1)
+	actual1, _ := BeeAnnotator.AnnotateToJson(Annotation1)
+	actual2, _ := BeeAnnotator.AnnotateToJson("")
 
-	assert.Equal(t, expect, actual)
+	assert.Equal(t, expect1, actual1)
+	assert.Equal(t, "", actual2)
 }
 
 func TestHandleWhitespaceValues(t *testing.T) {