code: protected boolean isGzipResponse(PostMethod postMethod) {
          Header encodingHeader = postMethod.getResponseHeader(HTTP_HEADER_CONTENT_ENCODING);
          return (encodingHeader != null && encodingHeader.getValue() != null &&
                  encodingHeader.getValue().toLowerCase().contains(ENCODING_GZIP));
      }
docs: Determine whether the given response indicates a GZIP response.
  <p>The default implementation checks whether the HTTP "Content-Encoding"
  header contains "gzip" (in any casing).
  @param postMethod the PostMethod to check
  @return whether the given response indicates a GZIP response