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 script;
        CTxDestination dest;
        if (!isScript) {
            dest = DecodeDestination(output);
            if (!IsValidDestination(dest)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
            }
            script = GetScriptForDestination(dest);
        } else {
            if (!IsHex(output)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid scriptPubKey");
            }
            std::vector<unsigned char> vData(ParseHex(output));
            script = CScript(vData.begin(), vData.end());
            if (!ExtractDestination(script, dest) && !internal) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Internal must be set to true for nonstandard scriptPubKey imports.");
            }
        }
        
        if (watchOnly && keys.size()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Watch-only addresses should not include private keys");
        }
        
        if (internal && data.exists("label")) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Internal addresses should not have a label");
        }
        
        if (!strRedeemScript.empty() && script.IsPayToWitnessScriptHash()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "P2WSH addresses have an empty redeemscript. Please provide the witnessscript instead.");