code: @Override
  	public boolean apply(HttpResponse x) {
  		final Header header = x.getFirstHeader(HttpHeaders.CONTENT_TYPE);
  		return header != null && header.getValue().startsWith(prefix);
  	}
docs: Apply the filter to a <code>HttpResponse</code>
  
  @param x the <code>HttpResponse</code> to be filtered
  @return <code>true</code> if the first header of the given <code>HttpResponse</code> is not null and starts with the prefix