Args.notNull(statusLine, "Status line");
Args.notNull(responseHeaders, "Response headers");
this.requestDate = requestDate;
this.responseDate = responseDate;
this.statusLine = statusLine;
this.responseHeaders = new HeaderGroup();
this.responseHeaders.setHeaders(responseHeaders);
this.resource = resource;
this.variantMap = variantMap != null
? new HashMap<String,String>(variantMap)
: null;