During initializing : syntax error, unexpected tLABEL

Hey everyone,

Version: 4.3.2
Operating System: server linux
Logstash version : 5.6
ruby : 1.9

Since this morning, I'm faced to a bug that I never received before.

SyntaxError: /usr/share/logstash/vendor/bundle/jruby/1.9/gems/logstash-output-s3-4.3.2/lib/logstash/outputs/s3/uploader.rb:19: syntax error, unexpected tLABEL
        def initialize(bucket, logger, threadpool = DEFAULT_THREADPOOL, retry_count: Float::INFINITY, retry_delay: 1)
                                                                                    ^

I'm trying to running a logstash script by outputting the result in S3 :

output {
  s3{
    access_key_id => "MY_ACCESS_KEY_ID"
    secret_access_key => "MY_SECRET_ACCESS_KEY"
    region => "eu-west-1"
    bucket => "dev-import-bucket"
    rotation_strategy => "size"
    codec => "json_lines"
  }
}

I don't see where i'm wrong. When I print the output :

stdout {
       codec => json_lines
    }

I have the expected result. It happens just when there is the initialize... but honestly, no clue. Any idea ?

Thanks

logstash-plugins / logstash-output-s3

During initializing : syntax error, unexpected tLABEL #229