private LastHttpContent convertTrailers(HttpHeaders inputHeaders) {
        if (inputHeaders.isEmpty()) {
            return LastHttpContent.EMPTY_LAST_CONTENT;
        }

        final LastHttpContent lastContent = new DefaultLastHttpContent(Unpooled.EMPTY_BUFFER, false);
        final io.netty.handler.codec.http.HttpHeaders outputHeaders = lastContent.trailingHeaders();
        convertTrailers(inputHeaders, outputHeaders);
        return lastContent;
    }
The map which maps a request ID to its related pending response.
core/src/main/java/com/linecorp/armeria/internal/common/Http1ObjectEncoder.java