@Override
    public void write(ByteBuffer buf, CompletionHandler completionHandler) {
        if (buf.hasArray()) {
            accumulatedRequestContent.write(buf.array(), buf.arrayOffset() + buf.position(), buf.remaining());
        } else {
            var bytes = new byte[buf.remaining()];
            buf.get(bytes);
            accumulatedRequestContent.write(bytes, 0, bytes.length);
        }
        completionHandler.completed();
    }
@param delegateHandler the "real" request handler that this handler wraps
@param contentCharsetName name of the charset to use when interpreting the content data
container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/FormPostRequestHandler.java