Specifically, it adds an address into the wallet.

Easy to test now thanks to https://github.com/bitcoin/bitcoin/pull/14410
```
diff --git a/test/functional/wallet_importmulti.py b/test/functional/wallet_importmulti.py
index 9ba6860..bff37b2 100755
--- a/test/functional/wallet_importmulti.py
+++ b/test/functional/wallet_importmulti.py
@@ -95,6 +95,7 @@ class ImportMultiTest(BitcoinTestFramework):
         assert_equal(address_assert['iswatchonly'], True)
         assert_equal(address_assert['ismine'], False)
         assert_equal(address_assert['timestamp'], timestamp)
+        assert_equal(address_assert['ischange'], True)
 
         # ScriptPubKey + internal + label
         self.log.info("Should not allow a label to be specified when internal is true")
```

}
        for (const UniValue& data : requests.getValues()) {
            const int64_t timestamp = std::max(GetImportTimestamp(data, now), minimumTimestamp);
            const UniValue result = ProcessImport(pwallet, data, timestamp);
            response.push_back(result);
            if (!fRescan) {
                continue;
            }
            
            if (result["success"].get_bool()) {
                fRunScan = true;
            }
            
            if (timestamp < nLowestTimestamp) {
                nLowestTimestamp = timestamp;
            }
        }
    }
    if (fRescan && fRunScan && requests.size()) {
        int64_t scannedTime = pwallet->RescanFromTime(nLowestTimestamp, reserver, true );
        pwallet->ReacceptWalletTransactions();
        if (pwallet->IsAbortingRescan()) {
            throw JSONRPCError(RPC_MISC_ERROR, "Rescan aborted by user.");
        }
        if (scannedTime > nLowestTimestamp) {
            std::vector<UniValue> results = response.getValues();
            response.clear();
            response.setArray();
            size_t i = 0;
            for (const UniValue& request : requests.getValues()) {