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(pwallet->GetCScript(scriptid, script)) {
            file << strprintf("%s %s script=1", HexStr(script.begin(), script.end()), create_time);
            file << strprintf(" # addr=%s\n", address);
        }
    }
    file << "\n";
    file << "# End of dump\n";
    file.close();
    UniValue reply(UniValue::VOBJ);
    reply.pushKV("filename", filepath.string());
    return reply;
}
static UniValue ProcessImport(CWallet * const pwallet, const UniValue& data, const int64_t timestamp) EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)
{
    try {
        
        const UniValue& scriptPubKey = data["scriptPubKey"];
        bool isScript = scriptPubKey.getType() == UniValue::VSTR;
        if (!isScript && !(scriptPubKey.getType() == UniValue::VOBJ && scriptPubKey.exists("address"))) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "scriptPubKey must be string with script or JSON with address string");
        }
        const std::string& output = isScript ? scriptPubKey.get_str() : scriptPubKey["address"].get_str();
        
        const std::string& strRedeemScript = data.exists("redeemscript") ? data["redeemscript"].get_str() : "";
        const std::string& witness_script_hex = data.exists("witnessscript") ? data["witnessscript"].get_str() : "";
        const UniValue& pubKeys = data.exists("pubkeys") ? data["pubkeys"].get_array() : UniValue();
        const UniValue& keys = data.exists("keys") ? data["keys"].get_array() : UniValue();
        const bool internal = data.exists("internal") ? data["internal"].get_bool() : false;
        const bool watchOnly = data.exists("watchonly") ? data["watchonly"].get_bool() : false;
        const std::string& label = data.exists("label") ? data["label"].get_str() : "";