org.apache.knox.gateway.filter.rewrite.impl.UrlRewriteResponse employs java.util.zip.GZIPInputStream for gzipped content streams.
There appears to be an expectation in the GZIPInputStream of the InputStream#available() method, for which the behavior is varied across InputStream implementations. InputStream implementations that do not satisfy this expectation cause the GZIPInputStream to terminate prematurely, resulting in only partial reads.
There is an OpenJDK bug (https://bugs.openjdk.java.net/browse/JDK-8081450) for this, and the Oracle JDK suffers from the same.
This can be overcome in Knox with code.