**MultipleTopicsCollaborationAvatarGroup** is a **CollaborationAvatarGroup** to show the union of participants across multiple Collaboration Engine topics in a single avatar group. This is helpful when multiple collaborative documents ("Topics") are on screen (in the view) at the same time. **MultipleTopicsCollaborationAvatarGroup** extends Vaadin's `CollaborationAvatarGroup` to show the union of participants across multiple Collaboration Engine topics in a single avatar group. In a typical Collaboration Engine app, each topic has its own participant list. This component aggregates them: a user appears once in the avatar group as soon as they are registered as a participant in any of the added topics. When they leave all topics, they disappear. ## Features - `addTopic(topicId)` / `removeTopic(topicId)` — subscribe to participant topics dynamically - `setTopic(topicId)` — replaces all current topics (single-topic mode) - `setOwnAvatarVisible(boolean)` — show or hide the current user's avatar - `setImageHandler(handler)` — custom avatar images per user - Fully compatible with `CollaborationEngine.openTopicConnection` participant maps ## Usage ```java MultipleTopicsCollaborationAvatarGroup avatarGroup = new MultipleTopicsCollaborationAvatarGroup(userInfo); avatarGroup.addTopic("chat-room-1-participants"); avatarGroup.addTopic("chat-room-2-participants"); avatarGroup.addTopic("chat-room-3-participants"); ```