refactor: convert fetchBodyCallback class from java to kotlin

package com.fsck.k9.mail.store.imap;

package com.fsck.k9.mail.store.imap

import com.fsck.k9.mail.MessagingException

import com.fsck.k9.mail.filter.FixedLengthInputStream

import java.io.IOException

import java.io.IOException;

import java.util.Map;

const val LITERAL_HANDLED = 1

import com.fsck.k9.mail.MessagingException;

import com.fsck.k9.mail.filter.FixedLengthInputStream;

internal class FetchBodyCallback(private val messageMap: Map<String, ImapMessage>) : ImapResponseCallback {

    @Throws(MessagingException::class, IOException::class)

    override fun foundLiteral(

        response: ImapResponse,

        literal: FixedLengthInputStream,

    ): Any? {

        if (response.tag == null &&

            ImapResponseParser.equalsIgnoreCase(response[1], "FETCH")

        ) {

            val fetchList = response.getKeyedValue("FETCH") as ImapList

            val uid = fetchList.getKeyedString("UID")

class FetchBodyCallback implements ImapResponseCallback {

    private Map<String, ImapMessage> mMessageMap;

    FetchBodyCallback(Map<String, ImapMessage> messageMap) {

        mMessageMap = messageMap;

    }

    @Override

    public Object foundLiteral(ImapResponse response,

                               FixedLengthInputStream literal) throws MessagingException, IOException {

        if (response.getTag() == null &&

                ImapResponseParser.equalsIgnoreCase(response.get(1), "FETCH")) {

            ImapList fetchList = (ImapList)response.getKeyedValue("FETCH");

            String uid = fetchList.getKeyedString("UID");

            ImapMessage message = mMessageMap.get(uid);

            message.parse(literal);

            val message = messageMap[uid]

            message?.parse(literal)

            // Return placeholder object

            return 1;

            return LITERAL_HANDLED

        }

        return null;

        return null

    }

}