public void TestInvalidClientIds()
        {
            var badChars = new List <string> {
                "/", "\\", ",", "\0", ":", "\"", "\'", ";", "*", "?", " ", "\t", "\r", "\n", "="
            };
            var invalidClientIds = badChars.Select(weirdChar => "Is " + weirdChar + "illegal").ToList();

            foreach (var invalidClientId in invalidClientIds)
            {
                try
                {
                    ProducerConfig.ValidateClientId(invalidClientId);
                    Assert.False(true);
                }
                catch
                {
                }
            }

            var validClientIds = new List <string> {
                "valid", "CLIENT", "iDs", "ar6", "VaL1d", "_0-9_.", string.Empty
            };

            foreach (string validClientId in validClientIds)
            {
                ProducerConfig.ValidateClientId(validClientId);
            }
        }