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")
```

static const boost::posix_time::ptime epoch = boost::posix_time::from_time_t(0);
    static const std::locale loc(std::locale::classic(),
        new boost::posix_time::time_input_facet("%Y-%m-%dT%H:%M:%SZ"));
    std::istringstream iss(str);
    iss.imbue(loc);
    boost::posix_time::ptime ptime(boost::date_time::not_a_date_time);
    iss >> ptime;
    if (ptime.is_not_a_date_time())
        return 0;
    return (ptime - epoch).total_seconds();
}
std::string static EncodeDumpString(const std::string &str) {