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")
```

#include <chain.h>
#include <key_io.h>
#include <rpc/server.h>
#include <validation.h>
#include <script/script.h>
#include <script/standard.h>
#include <sync.h>
#include <util/system.h>
#include <util/time.h>
#include <wallet/wallet.h>
#include <merkleblock.h>
#include <core_io.h>
#include <wallet/rpcwallet.h>
#include <stdint.h>
#include <boost/algorithm/string.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <univalue.h>
int64_t static DecodeDumpTime(const std::string &str) {