Added logging for failed mqtt ssl certificates

common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttSslHandlerProvider.java

@@ -177,6 +177,7 @@ public class MqttSslHandlerProvider {
                 }
             }
             if (credentialsBody == null) {
+                log.debug("Failed to find credentials for device certificate chain: {}", (Object) chain);
                 throw new CertificateException("Invalid Device Certificate");
             }
         }