Class MergeTransfer<T>

Aggregator of multiple sources into a single stream (merge).

Capabilities: isInput, isOutput, isSubscribable

Mechanics:

1. The constructor accepts config.sources: an array of SubscribableTransferInterface
2. Automatically subscribes to all sources
3. On receiving data from any source — notifies its subscribers
4. subscribe(handler) — subscribes to the merged stream
5. destroy() — unsubscribes from all sources, unsubscribes its subscribers

Configuration (MergeTransferConfig):

• sources: SubscribableTransferInterface[] — data sources

Difference from AggregatorTransfer (old version):

• The new version uses SubscriptionManager and DisposableSubscriberAdapter
• Implements push/pull flags, but push() is only called internally

Use cases:

• Merging events from multiple sources (e.g., clicks + touch + keyboard)
• Multicast: one subscriber to multiple transfers
• Implementing BridgeAggregator