fix: change millisecond time format

If millisecond in go time is empty
they will be not exist in result string
if using "999" in format. And jira api
will response with error in the case.

Using "000" fix the problem.

Add test for time marshaling.

issue.go

@@ -351,7 +351,7 @@ func (t *Time) UnmarshalJSON(b []byte) error {
 // MarshalJSON will transform the time.Time into a JIRA time
 // during the creation of a JIRA request
 func (t Time) MarshalJSON() ([]byte, error) {
-	return []byte(time.Time(t).Format("\"2006-01-02T15:04:05.999-0700\"")), nil
+	return []byte(time.Time(t).Format("\"2006-01-02T15:04:05.000-0700\"")), nil
 }
 
 // UnmarshalJSON will transform the JIRA date into a time.Time

issue_test.go

@@ -9,11 +9,9 @@ import (
 	"reflect"
 	"strings"
 	"testing"
-
-	"github.com/google/go-cmp/cmp"
-
 	"time"
 
+	"github.com/google/go-cmp/cmp"
 	"github.com/trivago/tgo/tcontainer"
 )
 
@@ -1799,3 +1797,34 @@ func TestIssueService_AddRemoteLink(t *testing.T) {
 		t.Errorf("Error given: %s", err)
 	}
 }
+
+func TestTime_MarshalJSON(t *testing.T) {
+	timeFormatParseFrom := "2006-01-02T15:04:05.999Z"
+	testCases := []struct {
+		name      string
+		inputTime string
+		expected  string
+	}{
+		{
+			name:      "test without ms",
+			inputTime: "2020-04-01T01:01:01.000Z",
+			expected:  "\"2020-04-01T01:01:01.000+0000\"",
+		},
+		{
+			name:      "test with ms",
+			inputTime: "2020-04-01T01:01:01.001Z",
+			expected:  "\"2020-04-01T01:01:01.001+0000\"",
+		},
+	}
+
+	for _, tt := range testCases {
+		t.Run(tt.name, func(t *testing.T) {
+			rawTime, _ := time.Parse(timeFormatParseFrom, tt.inputTime)
+			time := Time(rawTime)
+			got, _ := time.MarshalJSON()
+			if string(got) != tt.expected {
+				t.Errorf("Time.MarshalJSON() = %v, want %v", string(got), tt.expected)
+			}
+		})
+	}
+}