@Override
    public ContentChannel handleRequest(Request request, ResponseHandler responseHandler) {
        Preconditions.checkArgument(request instanceof HttpRequest, "Expected HttpRequest, got " + request);
        Objects.requireNonNull(responseHandler, "responseHandler");

        this.contentCharset = getCharsetByName(contentCharsetName);
        this.responseHandler = responseHandler;
        this.request = (HttpRequest) request;

        return this;
    }
@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