Json metadata does not support serialize feature

[glebmikulko]

After initial gem setup with t.json :metadata, default: {} field I've got this error:

ActiveRecord::AttributeMethods::Serialization::ColumnNotSerializableError: Column `metadata` of type ActiveRecord::Type::Json does not support `serialize` feature.
Usually it means that you are trying to use `serialize`
on a column that already implements serialization natively.
from /home/gleb/.rbenv/versions/2.7.0/lib/ruby/gems/2.7.0/gems/activerecord-6.0.2.1/lib/active_record/attribute_methods/serialization.rb:74:in `block in serialize'

Environment:
Ruby 2.7.0
Rails 6.0.2.1
Postgres 11

[dferdian]

As per https://github.com/gocardless/statesman#using-postgresql-json-column, you need to remove the include Statesman::Adapters::ActiveRecordTransition statement from your transition model