Add logic to handle sending a common payload to multiple recipients

service/src/main/java/org/whispersystems/textsecuregcm/entities/MultiRecipientMessage.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.entities;
+
+import java.util.UUID;
+import javax.validation.constraints.Min;
+import javax.validation.constraints.NotNull;
+import javax.validation.constraints.Size;
+import org.whispersystems.textsecuregcm.providers.MultiRecipientMessageProvider;
+
+public class MultiRecipientMessage {
+
+  public static class Recipient {
+
+    @NotNull
+    private final UUID uuid;
+
+    @Min(1)
+    private final long deviceId;
+
+    @Size(min = 48, max = 48)
+    @NotNull
+    private final byte[] perRecipientKeyMaterial;
+
+    public Recipient(UUID uuid, long deviceId, byte[] perRecipientKeyMaterial) {
+      this.uuid = uuid;
+      this.deviceId = deviceId;
+      this.perRecipientKeyMaterial = perRecipientKeyMaterial;
+    }
+
+    public UUID getUuid() {
+      return uuid;
+    }
+
+    public long getDeviceId() {
+      return deviceId;
+    }
+
+    public byte[] getPerRecipientKeyMaterial() {
+      return perRecipientKeyMaterial;
+    }
+  }
+
+  @NotNull
+  @Size(min = 1, max = MultiRecipientMessageProvider.MAX_RECIPIENT_COUNT)
+  private final Recipient[] recipients;
+
+  @NotNull
+  @Min(32)
+  private final byte[] commonPayload;
+
+  public MultiRecipientMessage(Recipient[] recipients, byte[] commonPayload) {
+    this.recipients = recipients;
+    this.commonPayload = commonPayload;
+  }
+
+  public Recipient[] getRecipients() {
+    return recipients;
+  }
+
+  public byte[] getCommonPayload() {
+    return commonPayload;
+  }
+}

service/src/main/java/org/whispersystems/textsecuregcm/entities/SendMessageResponse.java

@@ -6,16 +6,24 @@
 package org.whispersystems.textsecuregcm.entities;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import java.util.List;
+import java.util.UUID;
 
 public class SendMessageResponse {
 
   @JsonProperty
   private boolean needsSync;
 
+  @JsonProperty
+  private List<UUID> uuids404;
+
   public SendMessageResponse() {}
 
   public SendMessageResponse(boolean needsSync) {
     this.needsSync = needsSync;
   }
 
+  public SendMessageResponse(List<UUID> uuids404) {
+    this.uuids404 = uuids404;
+  }
 }