docs: protected boolean checkIfMatch(final HttpServletRequest request, final HttpServletResponse response, final Attributes resourceAttributes)
  			throws IOException {
  
  		final String eTag = resourceAttributes.getETag();
  		final String headerValue = request.getHeader("If-Match");
  		if (headerValue != null) {
  			if (headerValue.indexOf('*') == -1) {
  
  				final StringTokenizer commaTokenizer = new StringTokenizer(headerValue, ",");
  				boolean conditionSatisfied = false;
  
  				while (!conditionSatisfied && commaTokenizer.hasMoreTokens()) {
  					final String currentToken = commaTokenizer.nextToken();
  					if (currentToken.trim().equals(eTag))
  						conditionSatisfied = true;
  				}
  
  				// If none of the given ETags match, 412 Precodition failed is
  				// sent back
  				if (!conditionSatisfied) {
  					response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
  					return false;
  				}
  
  			}
  		}
  		return true;
  	}