GetStream · gpunto · Aug 6, 2026 · Aug 6, 2026
@@ -47,7 +47,6 @@ import io.getstream.chat.android.client.api2.model.dto.DownstreamReminderDto
 import io.getstream.chat.android.client.api2.model.dto.DownstreamReminderInfoDto
 import io.getstream.chat.android.client.api2.model.dto.DownstreamThreadDto
 import io.getstream.chat.android.client.api2.model.dto.DownstreamThreadInfoDto
-import io.getstream.chat.android.client.api2.model.dto.DownstreamThreadParticipantDto
 import io.getstream.chat.android.client.api2.model.dto.DownstreamUserBlockDto
 import io.getstream.chat.android.client.api2.model.dto.DownstreamUserDto
 import io.getstream.chat.android.client.api2.model.dto.DownstreamUserGroupDto
@@ -136,10 +135,12 @@ import io.getstream.chat.android.network.models.BlockUsersResponse
 import io.getstream.chat.android.network.models.DeviceResponse
 import io.getstream.chat.android.network.models.GetApplicationResponse
 import io.getstream.chat.android.network.models.UserGroupResponse
+import io.getstream.chat.android.network.models.UserResponse
 import java.util.Date
 import io.getstream.chat.android.network.models.Command as CommandDto
 import io.getstream.chat.android.network.models.FileUploadConfig as UploadConfigDto
 import io.getstream.chat.android.network.models.Role as RoleDto
+import io.getstream.chat.android.network.models.ThreadParticipant as ThreadParticipantDto
 import io.getstream.chat.android.network.models.UserGroupMember as UserGroupMemberDto
 
 @Suppress("TooManyFunctions", "LargeClass")
@@ -439,6 +440,26 @@ internal class DomainMapping(
             extraData = extraData,
         )
 
+    internal fun UserResponse.toDomain(): User =
+        User(
+            id = id,
+            role = role,
+            name = name.orEmpty(),
+            image = image.orEmpty(),
+            language = language,
+            banned = banned,
+            online = online,
+            createdAt = createdAt,
+            updatedAt = updatedAt,
+            lastActive = lastActive,
+            deactivatedAt = deactivatedAt,
+            teams = teams,
+            teamsRole = teamsRole.orEmpty(),
+            blockedUserIds = blockedUserIds,
+            avgResponseTime = avgResponseTime?.toLong(),
+            extraData = custom.mapNotNull { (key, value) -> value?.let { key to it } }.toMap(),
+        ).let(userTransformer::transform)
+
     internal fun DownstreamLocationDto.toDomain(): Location =
         Location(
             cid = channel_cid,
@@ -837,11 +858,11 @@ internal class DomainMapping(
         )
 
     /**
-     * Transforms [DownstreamThreadParticipantDto] into [ThreadParticipant]
+     * Transforms [ThreadParticipantDto] into [ThreadParticipant]
      */
-    internal fun DownstreamThreadParticipantDto.toDomain(): ThreadParticipant = ThreadParticipant(
-        user = user?.toDomain() ?: User(id = user_id),
-        lastThreadMessageAt = last_thread_message_at,
+    internal fun ThreadParticipantDto.toDomain(): ThreadParticipant = ThreadParticipant(
+        user = user?.toDomain() ?: User(id = userId.orEmpty()),
+        lastThreadMessageAt = lastThreadMessageAt,
     )
 
     /**

@@ -17,6 +17,7 @@
 package io.getstream.chat.android.client.api2.model.dto
 
 import com.squareup.moshi.JsonClass
+import io.getstream.chat.android.network.models.ThreadParticipant
 import java.util.Date
 
 /**
@@ -60,7 +61,7 @@
     val participant_count: Int,
     val read: List<DownstreamChannelUserRead>?,
     val reply_count: Int?,
-    val thread_participants: List<DownstreamThreadParticipantDto>?,
+    val thread_participants: List<ThreadParticipant>?,
     val title: String,
     val updated_at: Date,
     val extraData: Map<String, Any>,
@@ -98,26 +99,11 @@
     val reply_count: Int?,
     val participant_count: Int?,
     val active_participant_count: Int?,
-    val thread_participants: List<DownstreamThreadParticipantDto>?,
+    val thread_participants: List<ThreadParticipant>?,
     val last_message_at: Date?,
     val created_at: Date,
     val updated_at: Date,
     val deleted_at: Date?,
     val title: String,
     val extraData: Map<String, Any>,
 ) : ExtraDataDto
-
-/**
- * The DTO for Thread Participant.
- *
- * @param user_id The ID of the user (thread participant).
- * @param user The user as the thread participant. (Note: It is not always delivered, sometimes we only get the ID of
- * the user - [user_id]).
- * @param last_thread_message_at The date of the last message in the thread at the time of participation.
- */
-@JsonClass(generateAdapter = true)
-internal data class DownstreamThreadParticipantDto(
-    val user_id: String,
-    val user: DownstreamUserDto?,
-    val last_thread_message_at: Date?,
-)
@@ -45,6 +45,7 @@ import io.getstream.chat.android.client.parser2.adapters.DownstreamThreadInfoDto
 import io.getstream.chat.android.client.parser2.adapters.DownstreamUserDtoAdapter
 import io.getstream.chat.android.client.parser2.adapters.EventAdapterFactory
 import io.getstream.chat.android.client.parser2.adapters.ExactDateAdapter
+import io.getstream.chat.android.client.parser2.adapters.NullCollectionsAsEmptyFactory
 import io.getstream.chat.android.client.parser2.adapters.PollOptionInputAdapter
 import io.getstream.chat.android.client.parser2.adapters.PollOptionRequestAdapter
 import io.getstream.chat.android.client.parser2.adapters.UpdatePollOptionRequestAdapter
@@ -55,6 +56,7 @@ import io.getstream.chat.android.client.parser2.adapters.UpstreamMessageDtoAdapt
 import io.getstream.chat.android.client.parser2.adapters.UpstreamReactionDtoAdapter
 import io.getstream.chat.android.client.parser2.adapters.UpstreamUserDtoAdapter
 import io.getstream.chat.android.client.parser2.adapters.UserRequestAdapter
+import io.getstream.chat.android.client.parser2.adapters.UserResponseAdapter
 import io.getstream.chat.android.client.socket.ErrorResponse
 import io.getstream.chat.android.client.socket.SocketErrorMessage
 import io.getstream.chat.android.network.infrastructure.Serializer
@@ -82,6 +84,7 @@ internal class MoshiChatParser(
             .add(UpstreamReactionDtoAdapter)
             .add(DownstreamUserDtoAdapter)
             .add(UpstreamUserDtoAdapter)
+            .add(UserResponseAdapter)
             .add(UserRequestAdapter)
             .add(DownstreamMemberDtoAdapter)
             .add(UpstreamMemberDtoAdapter)
@@ -105,6 +108,8 @@ internal class MoshiChatParser(
                 UpdatePollRequest.VotingVisibility::class.java,
                 UpdatePollRequest.VotingVisibility.VotingVisibilityAdapter(),
             )
+            // Registered last so the model-specific adapters above keep precedence and delegate into it.
+            .add(NullCollectionsAsEmptyFactory)
             .build()
     }
 

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2014-2026 Stream.io Inc. All rights reserved.
+ *
+ * Licensed under the Stream License;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://github.com/GetStream/stream-chat-android/blob/main/LICENSE
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.getstream.chat.android.client.parser2.adapters
+
+import com.squareup.moshi.Json
+import com.squareup.moshi.JsonAdapter
+import com.squareup.moshi.JsonReader
+import com.squareup.moshi.JsonWriter
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.Types
+import com.squareup.moshi.rawType
+import java.lang.reflect.Type
+import kotlin.reflect.full.findAnnotation
+import kotlin.reflect.full.primaryConstructor
+
+/**
+ * Reads an explicit `null` as an empty collection for the non-null [List] and [Map] properties of
+ * the generated network models.
+ *
+ * The models are generated from the v2 spec, whose encoder writes nil Go maps and slices as `{}`
+ * and `[]`, so those properties are non-null. We call the v1 endpoints, whose encoder writes them
+ * as `null` instead (e.g. `thread_participants[].custom`), which would otherwise fail to parse.
+ *
+ * Remove once the client calls the v2 endpoints, where the shape already matches the models.
+ */
+internal object NullCollectionsAsEmptyFactory : JsonAdapter.Factory {
+
+    private const val GENERATED_MODELS_PACKAGE = "io.getstream.chat.android.network.models"
+
+    override fun create(type: Type, annotations: MutableSet<out Annotation>, moshi: Moshi): JsonAdapter<*>? {
+        if (annotations.isNotEmpty()) return null
+        val rawType = type.rawType
+        if (rawType.`package`?.name != GENERATED_MODELS_PACKAGE) return null
+
+        val emptyValues = emptyValuesByJsonName(rawType)
+        if (emptyValues.isEmpty()) return null
+
+        return NullCollectionsAsEmptyAdapter(
+            delegate = moshi.nextAdapter(this, type, annotations),
+            mapAdapter = moshi.adapter(
+                Types.newParameterizedType(Map::class.java, String::class.java, Any::class.java),
+            ),
+            emptyValues = emptyValues,
+        )
+    }
+
+    /**
+     * Wire names of the non-null collection properties of [rawType], mapped to their empty value.
+     *
+     * Relies on the Kotlin metadata of the generated models, which `consumer-proguard-rules.pro`
+     * keeps. Failures are deliberately not caught: swallowing them would silently stop coercing
+     * nulls and turn this into a release-only parsing crash.
+     */
+    private fun emptyValuesByJsonName(rawType: Class<*>): Map<String, Any> =
+        rawType.kotlin.primaryConstructor?.parameters
+            .orEmpty()
+            .mapNotNull { parameter ->
+                if (parameter.type.isMarkedNullable) return@mapNotNull null
+                val empty: Any = when (parameter.type.classifier) {
+                    List::class -> emptyList<Any?>()
+                    Map::class -> emptyMap<String, Any?>()
+                    else -> return@mapNotNull null
+                }
+                val name = parameter.findAnnotation<Json>()?.name ?: parameter.name ?: return@mapNotNull null
+                name to empty
+            }
+            .toMap()
+}
+
+private class NullCollectionsAsEmptyAdapter(
+    private val delegate: JsonAdapter<Any>,
+    private val mapAdapter: JsonAdapter<MutableMap<String, Any?>>,
+    private val emptyValues: Map<String, Any>,
+) : JsonAdapter<Any>() {
+
+    override fun fromJson(reader: JsonReader): Any? {
+        if (reader.peek() == JsonReader.Token.NULL) {
+            return reader.nextNull()
+        }
+        val map = mapAdapter.fromJson(reader) ?: return null
+        emptyValues.forEach { (name, empty) ->
+            if (map.containsKey(name) && map[name] == null) {
+                map[name] = empty
+            }
+        }
+        return delegate.fromJsonValue(map)
+    }
+
+    override fun toJson(writer: JsonWriter, value: Any?) = delegate.toJson(writer, value)
+}
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2014-2026 Stream.io Inc. All rights reserved.
+ *
+ * Licensed under the Stream License;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://github.com/GetStream/stream-chat-android/blob/main/LICENSE
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.getstream.chat.android.client.parser2.adapters
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.JsonAdapter
+import com.squareup.moshi.JsonReader
+import com.squareup.moshi.JsonWriter
+import com.squareup.moshi.ToJson
+import io.getstream.chat.android.network.models.UserResponse
+
+// Downstream (read-only) adapter for the generated UserResponse: collects root-level custom fields
+// into `custom`, matching the wire's flattened extra data. extraDataPropertyName is its @Json name.
+internal object UserResponseAdapter :
+    CustomObjectDtoAdapter<UserResponse>(UserResponse::class, extraDataPropertyName = "custom") {
+
+    @FromJson
+    fun fromJson(
+        jsonReader: JsonReader,
+        mapAdapter: JsonAdapter<MutableMap<String, Any>>,
+        valueAdapter: JsonAdapter<UserResponse>,
+    ): UserResponse? = parseWithExtraData(jsonReader, mapAdapter, valueAdapter)
+
+    @ToJson
+    @Suppress("UNUSED_PARAMETER")
+    fun toJson(jsonWriter: JsonWriter, value: UserResponse): Unit = error("Can't convert this to Json")
+}
@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2014-2026 Stream.io Inc. All rights reserved.
+ *
+ * Licensed under the Stream License;
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    https://github.com/GetStream/stream-chat-android/blob/main/LICENSE
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+@file:Suppress(
+    "ArrayInDataClass",
+    "EnumEntryName",
+    "RemoveRedundantQualifierName",
+    "UnusedImport",
+)
+
+package io.getstream.chat.android.network.models
+
+import com.squareup.moshi.Json
+
+/**
+ * Represents a user that is participating in a thread.
+ */
+@com.squareup.moshi.JsonClass(generateAdapter = true)
+internal data class ThreadParticipant(
+    @Json(name = "app_pk")
+    internal val appPk: Int,
+
+    @Json(name = "channel_cid")
+    internal val channelCid: String,
+
+    @Json(name = "created_at")
+    internal val createdAt: java.util.Date,
+
+    @Json(name = "last_read_at")
+    internal val lastReadAt: java.util.Date,
+
+    @Json(name = "custom")
+    internal val custom: Map<String, Any?> = emptyMap(),
+
+    @Json(name = "last_thread_message_at")
+    internal val lastThreadMessageAt: java.util.Date? = null,
+
+    @Json(name = "left_thread_at")
+    internal val leftThreadAt: java.util.Date? = null,
+
+    @Json(name = "thread_id")
+    internal val threadId: String? = null,
+
+    @Json(name = "user_id")
+    internal val userId: String? = null,
+
+    @Json(name = "user")
+    internal val user: io.getstream.chat.android.network.models.UserResponse? = null,
+)