Server side support for delivery receipts.

src/main/java/org/whispersystems/textsecuregcm/entities/IncomingMessage.java

@@ -41,7 +41,7 @@ public class IncomingMessage {
   private String relay;
 
   @JsonProperty
-  private long   timestamp;
+  private long   timestamp; // deprecated
 
 
   public String getDestination() {

src/main/java/org/whispersystems/textsecuregcm/entities/IncomingMessageList.java

@@ -32,6 +32,9 @@ public class IncomingMessageList {
   @JsonProperty
   private String relay;
 
+  @JsonProperty
+  private long timestamp;
+
   public IncomingMessageList() {}
 
   public List<IncomingMessage> getMessages() {
@@ -45,4 +48,8 @@ public class IncomingMessageList {
   public void setRelay(String relay) {
     this.relay = relay;
   }
+
+  public long getTimestamp() {
+    return timestamp;
+  }
 }

src/main/java/org/whispersystems/textsecuregcm/entities/PendingMessage.java

@@ -13,11 +13,15 @@ public class PendingMessage {
   @JsonProperty
   private String encryptedOutgoingMessage;
 
+  @JsonProperty
+  private boolean receipt;
+
   public PendingMessage() {}
 
-  public PendingMessage(String sender, long messageId, String encryptedOutgoingMessage) {
+  public PendingMessage(String sender, long messageId, boolean receipt, String encryptedOutgoingMessage) {
     this.sender                    = sender;
     this.messageId                 = messageId;
+    this.receipt                   = receipt;
     this.encryptedOutgoingMessage  = encryptedOutgoingMessage;
   }
 
@@ -33,6 +37,10 @@ public class PendingMessage {
     return sender;
   }
 
+  public boolean isReceipt() {
+    return receipt;
+  }
+
   @Override
   public boolean equals(Object other) {
     if (other == null || !(other instanceof PendingMessage)) return false;
@@ -41,11 +49,12 @@ public class PendingMessage {
     return
         this.sender.equals(that.sender) &&
         this.messageId == that.messageId &&
+        this.receipt == that.receipt     &&
         this.encryptedOutgoingMessage.equals(that.encryptedOutgoingMessage);
   }
 
   @Override
   public int hashCode() {
-    return this.sender.hashCode() ^ (int)this.messageId ^ this.encryptedOutgoingMessage.hashCode();
+    return this.sender.hashCode() ^ (int)this.messageId ^ this.encryptedOutgoingMessage.hashCode() ^ (receipt ? 1 : 0);
   }
 }