void (URLConnection connection) { for (Map.Entry<String, List<String>> header : connection.getRequestProperties().entrySet()) { for (String headerValue : header.getValue()) { if (headerValue.indexOf('\0') >= 0) { connection.setRequestProperty(header.getKey(), null); LOG.error(String.format("Problem during request to '%s'. Header's '%s' value contains NUL bytes: '%s'. Omitting this header.", connection.getURL().toString(), header.getKey(), headerValue)); break; } } } }