Add memoStr to z_listunspent output

src/wallet/rpcwallet.cpp

@@ -4217,6 +4217,14 @@ UniValue z_listunspent(const UniValue& params, bool fHelp, const CPubKey& mypk)
             obj.push_back(Pair("address", EncodePaymentAddress(entry.address)));
             obj.push_back(Pair("amount", ValueFromAmount(CAmount(entry.note.value())))); // note.value() is equivalent to plaintext.value()
             obj.push_back(Pair("memo", HexStr(entry.memo)));
+            auto memo = entry.memo;
+            if (memo[0] <= 0xf4) {
+                auto end = std::find_if(memo.rbegin(), memo.rend(), [](unsigned char v) { return v != 0; });
+                std::string memoStr(memo.begin(), end.base());
+                if (utf8::is_valid(memoStr)) {
+                    obj.push_back(Pair("memoStr", memoStr));
+                }
+            }
             if (hasSaplingSpendingKey) {
                 obj.push_back(Pair("change", pwalletMain->IsNoteSaplingChange(nullifierSet, entry.address, entry.op)));
             }