From: https://github.com/logstash-plugins/logstash-filter-mutate/blob/v3.3.1/lib/logstash/filters/mutate.rb#L247-L265 and: https://github.com/elastic/logstash/blob/v6.2.1/logstash-core/lib/logstash/filters/base.rb#L180-L212
- coerce
- rename
- update
- replace
- convert
- gsub
- uppercase
- capitalize
- lowercase
- strip
- remove
- split
- join
- merge
- copy
- (base)
- add_field
- remove_field
- add_tag
- remove_tag