default HttpRequest toHttpRequest(RequestHeaders headers) {
        requireNonNull(headers, "headers");
        return HttpRequest.of(headers, content(), trailers());
    }
Converts this request into a new complete {@link HttpRequest} replacing the {@link #headers()}
with the specified {@link RequestHeaders}.

@return the new {@link HttpRequest} converted from this request.
core/src/main/java/com/linecorp/armeria/common/AggregatedHttpRequest.java