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_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)
+			}
+		})
+	}
+}