[xianshijing-lk]

Port of livekit/client-sdk-js#2092.

The gap

RoomEvent.DataReceived.participant is nullable and is null whenever the sender is not in the room — data sent through the Server API, or by a participant who has already left. In that case the receiver cannot tell who sent the data at all; the identity is absent from the event.

Unlike the JS and Flutter SDKs, the identity was not merely unused here — it was discarded one layer earlier. RTCEngine unwraps the DataPacket and hands the listener only the inner UserPacket:

listener?.onUserPacket(dp.user, dp.kind, encryptionType)

The authoritative participantIdentity lives on the enclosing dp, so Room.onUserPacket never saw it and had nothing to put on the event.

The fix

Forward dp.participantIdentity through the internal RTCEngine.Listener.onUserPacket and surface it as DataReceived.participantIdentity, populated whether or not the sender resolves to a RemoteParticipant.

Verification

Added dataReceivedReportsSenderIdentityWithoutParticipant to RoomDataMockE2ETest, delivering a packet whose sender is not a room participant and asserting participant is null while the identity still arrives. Before the change it does not compile, since the field does not exist.

:livekit-android-test:testReleaseUnitTest green (both cases in that file run).

API notes

• participantIdentity is added as a constructor parameter with a "" default, so existing construction sites keep compiling.
• RTCEngine.Listener.onUserPacket gains a parameter. That interface is internal to the SDK and Room is its only implementor, so no public surface changes there.

Unrelated observation

While tracing this I noticed Room.onUserPacket resolves the sender with getParticipantBySid(packet.participantSid) — the inner packet's SID — whereas the JS and Flutter SDKs resolve by the outer packet's identity. Now that the identity is plumbed through, switching the lookup to it would also be possible. I have left the lookup alone here to keep this change focused; happy to file it separately if it's worth pursuing.

🤖 Generated with Claude Code

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🦋 Changeset detected

Latest commit: 7f191c2

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
client-sdk-android	Patch

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[github-actions]

Diffuse output:

OLD: diffuse-source-file
NEW: livekit-android-sdk-release.aar

 AAR      │ old      │ new      │ diff   
──────────┼──────────┼──────────┼────────
      jar │    3 MiB │    3 MiB │ +353 B 
 manifest │  1.5 KiB │  1.5 KiB │    0 B 
 lint-jar │ 12.7 KiB │ 12.7 KiB │    0 B 
    other │  2.4 KiB │  2.4 KiB │    0 B 
──────────┼──────────┼──────────┼────────
    total │    3 MiB │    3 MiB │ +353 B 

 JAR     │ old   │ new   │ diff       
─────────┼───────┼───────┼────────────
 classes │  1707 │  1707 │  0 (+0 -0) 
 methods │ 21992 │ 21995 │ +3 (+5 -2) 
  fields │  5708 │  5709 │ +1 (+1 -0)

AAR

 size  │ diff   │ path          
───────┼────────┼───────────────
 3 MiB │ +353 B │ ∆ classes.jar 
───────┼────────┼───────────────
 3 MiB │ +353 B │ (total)

JAR

METHODS:

   old   │ new   │ diff       
  ───────┼───────┼────────────
   21992 │ 21995 │ +3 (+5 -2) 
  
  + io.livekit.android.events.RoomEvent_DataReceived <init>(Room, byte[], RemoteParticipant, String, LivekitModels_Encryption_Type, String)
  + io.livekit.android.events.RoomEvent_DataReceived <init>(Room, byte[], RemoteParticipant, String, LivekitModels_Encryption_Type, String, int, DefaultConstructorMarker)
  + io.livekit.android.events.RoomEvent_DataReceived getParticipantIdentity() → String
  + io.livekit.android.room.RTCEngine_Listener onUserPacket(LivekitModels_UserPacket, LivekitModels_DataPacket_Kind, LivekitModels_Encryption_Type, String)
  + io.livekit.android.room.Room onUserPacket(LivekitModels_UserPacket, LivekitModels_DataPacket_Kind, LivekitModels_Encryption_Type, String)
  
  - io.livekit.android.room.RTCEngine_Listener onUserPacket(LivekitModels_UserPacket, LivekitModels_DataPacket_Kind, LivekitModels_Encryption_Type)
  - io.livekit.android.room.Room onUserPacket(LivekitModels_UserPacket, LivekitModels_DataPacket_Kind, LivekitModels_Encryption_Type)
  

FIELDS:

   old  │ new  │ diff       
  ──────┼──────┼────────────
   5708 │ 5709 │ +1 (+1 -0) 
  
  + io.livekit.android.events.RoomEvent_DataReceived participantIdentity: String