Adding a new field to body of the request from Netflix Zuul Pre-filter - filter

Question

I'm trying to add a new field to request's body, in a Zuul Pre-filter.
I'm using one of the Neflix's Zuul sample projects from here, and my filter's implementation is very similar to UppercaseRequestEntityFilter from this sample.
I was able to apply a transformation such as uppercase, or even to completely modify the request, the only inconvenient is that I'm not able to modify the content of body's request that has a length more than the original length of the body's request.
This is my filter's implementation:
#Component
public class MyRequestEntityFilter extends ZuulFilter {
public String filterType() {
return "pre";
}
public int filterOrder() {
return 10;
}
public boolean shouldFilter() {
RequestContext context = getCurrentContext();
return true;
}
public Object run() {
try {
RequestContext context = getCurrentContext();
InputStream in = (InputStream) context.get("requestEntity");
if (in == null) {
in = context.getRequest().getInputStream();
}
String body = StreamUtils.copyToString(in, Charset.forName("UTF-8"));
body = body.replaceFirst("qqq", "qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq");
// body = body.toUpperCase();
context.set("requestEntity", new ServletInputStreamWrapper(body.getBytes("UTF-8")));
}
catch (IOException e) {
rethrowRuntimeException(e);
}
return null;
}
}
This is the request that I'm doing:
This is the response that I'm receiving:

Answer 1

I was able to obtain what I wanted, using the implementation of PrefixRequestEntityFilter, from sample-zuul-examples:
#Component
public class MyRequestEntityFilter extends ZuulFilter {
public String filterType() {
return "pre";
}
public int filterOrder() {
return 10;
}
public boolean shouldFilter() {
RequestContext context = getCurrentContext();
return true;
}
public Object run() {
try {
RequestContext context = getCurrentContext();
InputStream in = (InputStream) context.get("requestEntity");
if (in == null) {
in = context.getRequest().getInputStream();
}
String body = StreamUtils.copyToString(in, Charset.forName("UTF-8"));
body = body.replaceFirst("qqq", "qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq");
byte[] bytes = body.getBytes("UTF-8");
context.setRequest(new HttpServletRequestWrapper(getCurrentContext().getRequest()) {
#Override
public ServletInputStream getInputStream() throws IOException {
return new ServletInputStreamWrapper(bytes);
}
#Override
public int getContentLength() {
return bytes.length;
}
#Override
public long getContentLengthLong() {
return bytes.length;
}
});
}
catch (IOException e) {
rethrowRuntimeException(e);
}
return null;
}
}