Corso: Exchange: Mail: Backup Details to include recipients --JSON ONLY (#2689)

<!-- Insert PR description-->
#### Adds  Email recipients to the backup details for Exchange Mail. If the recipients are of length greater than one, the list of individuals is included and separated by a `,`

---

#### Does this PR need a docs update or release note?
- [x] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature


#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* closes  #2687<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [x] ⚡ Unit test

src/internal/connector/exchange/api/mail.go

@@ -357,19 +357,28 @@ func (c Mail) Serialize(
 // ---------------------------------------------------------------------------
 
 func MailInfo(msg models.Messageable) *details.ExchangeInfo {
-	sender := ""
-	subject := ptr.Val(msg.GetSubject())
-	received := ptr.Val(msg.GetReceivedDateTime())
-	created := ptr.Val(msg.GetCreatedDateTime())
+	var (
+		sender     = graph.UnwrapEmailAddress(msg.GetSender())
+		subject    = ptr.Val(msg.GetSubject())
+		received   = ptr.Val(msg.GetReceivedDateTime())
+		created    = ptr.Val(msg.GetCreatedDateTime())
+		recipients = make([]string, 0)
+	)
 
-	if msg.GetSender() != nil &&
-		msg.GetSender().GetEmailAddress() != nil {
-		sender = ptr.Val(msg.GetSender().GetEmailAddress().GetAddress())
+	if msg.GetToRecipients() != nil {
+		ppl := msg.GetToRecipients()
+		for _, entry := range ppl {
+			temp := graph.UnwrapEmailAddress(entry)
+			if len(temp) > 0 {
+				recipients = append(recipients, temp)
+			}
+		}
 	}
 
 	return &details.ExchangeInfo{
 		ItemType:  details.ExchangeMail,
 		Sender:    sender,
+		Recipient: recipients,
 		Subject:   subject,
 		Received:  received,
 		Created:   created,

src/internal/connector/exchange/api/mail_test.go

@@ -36,6 +36,7 @@ func (suite *MailAPIUnitSuite) TestMailInfo() {
 
 				i := &details.ExchangeInfo{
 					ItemType:  details.ExchangeMail,
+					Recipient: []string{},
 					Created:   initial,
 					Modified:  initial,
 				}
@@ -56,6 +57,7 @@ func (suite *MailAPIUnitSuite) TestMailInfo() {
 				msg.SetSender(sr)
 				i := &details.ExchangeInfo{
 					ItemType:  details.ExchangeMail,
+					Recipient: []string{},
 					Sender:    sender,
 					Created:   initial,
 					Modified:  initial,
@@ -75,6 +77,7 @@ func (suite *MailAPIUnitSuite) TestMailInfo() {
 					ItemType:  details.ExchangeMail,
 					Subject:   subject,
 					Created:   initial,
+					Recipient: []string{},
 					Modified:  initial,
 				}
 				return msg, i
@@ -90,6 +93,7 @@ func (suite *MailAPIUnitSuite) TestMailInfo() {
 				msg.SetReceivedDateTime(&now)
 				i := &details.ExchangeInfo{
 					ItemType:  details.ExchangeMail,
+					Recipient: []string{},
 					Received:  now,
 					Created:   initial,
 					Modified:  initial,
@@ -101,22 +105,31 @@ func (suite *MailAPIUnitSuite) TestMailInfo() {
 			name: "All fields",
 			msgAndRP: func() (models.Messageable, *details.ExchangeInfo) {
 				sender := "foo@bar.com"
+				receiver := "foofoo@bar.com"
 				subject := "Hello world"
 				now := time.Now()
 				sr := models.NewRecipient()
 				sea := models.NewEmailAddress()
+				recv := models.NewRecipient()
+				req := models.NewEmailAddress()
+				recvs := make([]models.Recipientable, 0)
 				msg := models.NewMessage()
 				msg.SetCreatedDateTime(&initial)
 				msg.SetLastModifiedDateTime(&initial)
 				sea.SetAddress(&sender)
 				sr.SetEmailAddress(sea)
 				msg.SetSender(sr)
+				req.SetAddress(&receiver)
+				recv.SetEmailAddress(req)
 				msg.SetSubject(&subject)
 				msg.SetReceivedDateTime(&now)
+				recvs = append(recvs, recv, sr)
+				msg.SetToRecipients(recvs)
 				i := &details.ExchangeInfo{
 					ItemType:  details.ExchangeMail,
 					Sender:    sender,
 					Subject:   subject,
+					Recipient: []string{receiver, sender},
 					Received:  now,
 					Created:   initial,
 					Modified:  initial,

src/internal/connector/graph/shared.go

@@ -0,0 +1,18 @@
+package graph
+
+// Contains helper methods that are common across multiple
+// Microsoft Graph Applications.
+
+import (
+	"github.com/alcionai/corso/src/internal/common/ptr"
+	"github.com/microsoftgraph/msgraph-sdk-go/models"
+)
+
+func UnwrapEmailAddress(contact models.Recipientable) string {
+	var empty string
+	if contact == nil || contact.GetEmailAddress() == nil {
+		return empty
+	}
+
+	return ptr.Val(contact.GetEmailAddress().GetAddress())
+}

src/pkg/backup/details/details.go

@@ -516,6 +516,7 @@ type ExchangeInfo struct {
 	ItemType    ItemType  `json:"itemType,omitempty"`
 	Sender      string    `json:"sender,omitempty"`
 	Subject     string    `json:"subject,omitempty"`
+	Recipient   []string  `json:"recipient,omitempty"`
 	ParentPath  string    `json:"parentPath,omitempty"`
 	Received    time.Time `json:"received,omitempty"`
 	EventStart  time.Time `json:"eventStart,omitempty"`

src/pkg/backup/details/details_test.go

@@ -94,6 +94,7 @@ func (suite *DetailsUnitSuite) TestDetailsEntry_HeadersValues() {
 						ItemType:   ExchangeMail,
 						Sender:     "sender",
 						ParentPath: "Parent",
+						Recipient:  []string{"receiver"},
 						Subject:    "subject",
 						Received:   now,
 					},