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")
```

if (!witness_script_hex.empty() && script.IsPayToWitnessScriptHash()) {
            if (!IsHex(witness_script_hex)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid witness script: must be hex string");
            }
            
            std::vector<unsigned char> witness_script_parsed(ParseHex(witness_script_hex));
            CScript witness_script = CScript(witness_script_parsed.begin(), witness_script_parsed.end());
            CScriptID witness_id(witness_script);
            
            if (GetScriptForDestination(WitnessV0ScriptHash(witness_script)) != script) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "The witnessScript does not match the scriptPubKey or redeemScript");
            }
            
            if (!scriptpubkey_script.IsPayToScriptHash() && !pwallet->AddWatchOnly(witness_script, timestamp)) {
                throw JSONRPCError(RPC_WALLET_ERROR, "Error adding address to wallet");
            }
            if (!pwallet->HaveCScript(witness_id) && !pwallet->AddCScript(witness_script)) {
                throw JSONRPCError(RPC_WALLET_ERROR, "Error adding p2wsh witnessScript to wallet");
            }
            
            script = witness_script;
            ExtractDestination(script, dest);
            allow_p2wpkh = false; 
        }
        
        if (dest.type() == typeid(CKeyID) || dest.type() == typeid(WitnessV0KeyHash)) {
            if (!allow_p2wpkh && dest.type() == typeid(WitnessV0KeyHash)) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "P2WPKH cannot be embedded in P2WSH");
            }
            if (keys.size() > 1 || pubKeys.size() > 1) {