byte[] data = new byte[content.readableBytes()];
content.readBytes(data);
String responseToTransform = createStringFromData(data, charset);
RealURLToProxyURLMapping mapping = realToProxyURLMappingInst.get();
for (Map.Entry<URL, URL> entry : mapping.asMap().entrySet()) {
String realUrl = entry.getKey().toExternalForm();
String proxyUrl = entry.getValue().toExternalForm();
int urlStart = responseToTransform.indexOf(realUrl);