If I create an RBF transaction using the Qt GUI but specify my own custom change address, bumpfee doesn't work because it claims it can't find the change address:

    "Transaction does not have a change output"

This is because none of the outputs satisfy

    pWallet->IsChange(...)

I see there's a "TODO" commented in `CWallet::IsChange()` in `src/wallet/wallet.cpp`:

    // TODO: fix handling of 'change' outputs. The assumption is that any
    // payment to a script that is ours, but is not in the address book
    // is change.

I tend to put all my addresses in the address book whether I'm going to use them as change or not. I guess if the wallet was capable of creating its own SegWit change addresses I'd stop using custom change addresses, but currently it always seems to send change to a legacy address if I don't manually specify a change address.
"       \"ALL|ANYONECANPAY\"\n"
            "       \"NONE|ANYONECANPAY\"\n"
            "       \"SINGLE|ANYONECANPAY\""},
                },
                RPCResult{
                    RPCResult::Type::OBJ, "", "",
                    {
                        {RPCResult::Type::STR_HEX, "hex", "The hex-encoded raw transaction with signature(s)"},
                        {RPCResult::Type::BOOL, "complete", "If the transaction has a complete set of signatures"},
                        {RPCResult::Type::ARR, "errors", true, "Script verification errors (if there are any)",
                        {
                            {RPCResult::Type::OBJ, "", "",
                            {
                                {RPCResult::Type::STR_HEX, "txid", "The hash of the referenced, previous transaction"},
                                {RPCResult::Type::NUM, "vout", "The index of the output to spent and used as input"},
                                {RPCResult::Type::ARR, "witness", "",
                                {
                                    {RPCResult::Type::STR_HEX, "witness", ""},
                                }},
                                {RPCResult::Type::STR_HEX, "scriptSig", "The hex-encoded signature script"},
                                {RPCResult::Type::NUM, "sequence", "Script sequence number"},
                                {RPCResult::Type::STR, "error", "Verification or signing error related to the input"},
                            }},
                        }},
                    }
                },
                RPCExamples{
                    HelpExampleCli("signrawtransactionwithwallet", "\"myhex\"")
            + HelpExampleRpc("signrawtransactionwithwallet", "\"myhex\"")
                },