Set<String> fieldSet = (Set<String>) propMap.get(INDEX_ADMIN_ARRAY_FIELD_SET);
        if (fieldSet == null) {
            fieldSet = split(getIndexAdminArrayFields(), ",")
                    .get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).collect(Collectors.toSet()));
            propMap.put(INDEX_ADMIN_ARRAY_FIELD_SET, fieldSet);
        }
        return fieldSet;
    }

        try {
            final FileChannel channel = in.getChannel();
            final ByteBuffer buffer = ByteBuffer.allocate(DEFAULT_BUF_SIZE);
            final byte[] buf = buffer.array();
            int len;
            int amount = 0;
            while ((len = ChannelUtil.read(channel, buffer, amount)) != -1) {
                out.write(buf, 0, len);
                buffer.clear();