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")
```

}
        CScript scriptpubkey_script = script;
        CTxDestination scriptpubkey_dest = dest;
        bool allow_p2wpkh = true;
        
        if (!strRedeemScript.empty() && script.IsPayToScriptHash()) {
            
            if (!IsHex(strRedeemScript)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid redeem script: must be hex string");
            }
            
            std::vector<unsigned char> vData(ParseHex(strRedeemScript));
            CScript redeemScript = CScript(vData.begin(), vData.end());
            CScriptID redeem_id(redeemScript);
            
            if (GetScriptForDestination(redeem_id) != script) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "The redeemScript does not match the scriptPubKey");
            }
            pwallet->MarkDirty();
            if (!pwallet->AddWatchOnly(redeemScript, timestamp)) {
                throw JSONRPCError(RPC_WALLET_ERROR, "Error adding address to wallet");
            }
            if (!pwallet->HaveCScript(redeem_id) && !pwallet->AddCScript(redeemScript)) {
                throw JSONRPCError(RPC_WALLET_ERROR, "Error adding p2sh redeemScript to wallet");
            }
            
            script = redeemScript;
            ExtractDestination(script, dest);
        }