Create Draft Request
public CreateDraftRequest CreateDraftRequest(@Json(name = "to" ) List<EmailName> to, @Json(name = "bcc" ) List<EmailName> bcc, @Json(name = "cc" ) List<EmailName> cc, @Json(name = "reply_to" ) List<EmailName> replyTo, @Json(name = "attachments" ) List<CreateAttachmentRequest> attachments, @Json(name = "subject" ) String subject, @Json(name = "body" ) String body, @Json(name = "starred" ) Boolean starred, @Json(name = "send_at" ) Integer sendAt, @Json(name = "reply_to_message_id" ) String replyToMessageId, @Json(name = "tracking_options" ) TrackingOptions trackingOptions, @Json(name = "custom_headers" ) List<CustomHeader> customHeaders)