Custom Log Level Log4J

I would like to have a custom log level for some tests in my code. I using log4j in a java-project.
The needed level is created and works in my local console output, but I can not show the log in Kibana. I think it is a Problem with the Logstash config file but don’t know what I have to add for custom log levels.
I hope you can help me.

How are the messages sent to Logstash?

input {
log4j {
type => "log4j"
port => 5000
mode => "server"
here is the input of my logstash.config file.

log4j.rootLogger=INFO, server, stdout

and my properties file.

Yeah, I don't know of the log4j input supports custom log levels. I'd look in the Logstash logs for clues, raising the log level if needed.