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Wallet implementations may allow access to addresses generated from specific private keys or nonstandard HD derivation paths. The wallet will never offer these destinations as current payment targets. It will only spend them (and show their balance).
To inject "retrieve only" type of destination into the core wallet operation, override and implement this function. This function is only called during wallet initialization and rediscovery. Dynamic addition of destinations is not supported.
(note to future dev: dynamic addition is not hard in this architecture. Use electrum to find the UTXOs (and the TXOs if you want to import history) and add them and the destination to the appropriate CommonWallet data structures. Save and regenerate bloom.