Error initializing processors

Elastic Stack Beats
7

Yes, sure. Only 2 spaces in front of "when". Not working.

processors:
- drop_event:
  when.regexp.message: 'MicrosoftExchange.+@kirmarket\.ru'

In other parts of config file 2-spaced indentations works fine.

filebeat.prospectors:
  - input_type: log
    document_type: exchange
    paths:
      - d:\Program Files\Exchange Server 2013\TransportRoles\Logs\MessageTracking\MSGTRK2*.LOG
    ignore_older: 336h
    exclude_lines: ['MicrosoftExchange.+@kirmarket\.ru','HealthMailbox.+@kirmarket\.ru','postmaster@kirmarket\.ru']
    close_inactive: 2h

processors:
- drop_event:
  when.regexp.message: 'MicrosoftExchange.+@kirmarket\.ru'

output:
  logstash:
    hosts: ["logs:5044"]

Also, filebeat version is filebeat-5.5.0-windows-x86_64