Method onSubject

app/src/main/java/eu/faircode/email/Core.java:3315–3350

(Context context, JSONArray jargs, EntityAccount account, EntityFolder folder, EntityMessage message, IMAPStore istore, IMAPFolder ifolder, State state)

    }

    private static void onSubject(Context context, JSONArray jargs, EntityAccount account, EntityFolder folder, EntityMessage message, IMAPStore istore, IMAPFolder ifolder, State state) throws JSONException, MessagingException, IOException {
        DB db = DB.getInstance(context);

        String subject = (jargs.isNull(0) ? null : jargs.getString(0));

        EntityFolder trash = db.folder().getFolderByType(message.account, EntityFolder.TRASH);

        // Get message
        Message imessage = ifolder.getMessageByUID(message.uid);
        if (imessage == null)
            throw new MessageRemovedException();

        String msgid = EntityMessage.generateMessageId();
        String ref = (TextUtils.isEmpty(message.references)
                ? message.msgid
                : message.references + " " + message.msgid);
        MimeMessage icopy = new MimeMessageEx((MimeMessage) imessage, msgid);
        icopy.setSubject(subject); // Update or delete subject
        icopy.addHeader("References", MessageHelper.limitReferences(ref));
        icopy.addHeader(MessageHelper.HEADER_MODIFIED_TIME, Long.toString(new Date().getTime()));

        ifolder.appendMessages(new Message[]{icopy});

        Long uid = findUid(context, account, ifolder, msgid, null);
        if (uid != null) {
            JSONArray fargs = new JSONArray();
            fargs.put(uid);
            onFetch(context, fargs, folder, istore, ifolder, state);
        }

        if (trash == null) {
            imessage.setFlag(Flags.Flag.DELETED, true);
            expunge(context, ifolder, Arrays.asList(imessage));
        } else
            EntityOperation.queue(context, message, EntityOperation.MOVE, trash.id);
    }

    private static void onSynchronizeMessages(
            Context context, JSONArray jargs,