question: @ SuppressWarnings ( "unchecked" ) public static boolean isGzipSupported ( final HttpServletRequest request ) { if ( request != null ) { final Enumeration < String > headerNames = request . getHeaderNames ( ) ; if ( headerNames != null ) { while ( headerNames . hasMoreElements ( ) ) { final String headerName = headerNames . nextElement ( ) ; final Matcher m = PATTERN_ACCEPT_ENCODING . matcher ( headerName ) ; if ( m . find ( ) ) { final String headerValue = request . getHeader ( headerName ) ; final Matcher mValue = PATTERN_GZIP . matcher ( headerValue ) ; return mValue . find ( ) ; } } } } return false ; }
target:  Analyze headers of the request and searches for mangled (by proxy) for "Accept-Encoding" header and its mangled variations and gzip header value and its mangled variations.