vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0lib/mongo/server/connection_pool.rb:322:in `block in check_in': Trying to check in a connection which is not currently checked out by this pool: #<Mongo::Server::Connection:0x722dc377> (ArgumentError)
    from org/jruby/ext/thread/Mutex.java:165:in `synchronize'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/server/connection_pool.rb:320:in `check_in'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/server/connection_pool.rb:468:in `with_connection'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/server.rb:343:in `with_connection'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/operation/shared/executable.rb:41:in `dispatch_message'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/operation/shared/executable.rb:36:in `get_result'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/operation/shared/executable.rb:24:in `execute'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/operation/shared/executable_transaction_label.rb:27:in `execute'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/operation/shared/op_msg_or_find_command.rb:28:in `execute'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/collection/view/iterable.rb:89:in `send_initial_query'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/collection/view/iterable.rb:46:in `block in each'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/retryable.rb:61:in `block in read_with_retry_cursor'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/retryable.rb:250:in `legacy_read_with_retry'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/retryable.rb:119:in `read_with_retry'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/retryable.rb:60:in `read_with_retry_cursor'
    from vendor/bundle/jruby/2.5.0/gems/mongo-2.9.0/lib/mongo/collection/view/iterable.rb:45:in `each'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/query_cache.rb:227:in `each'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/contextual/mongo.rb:133:in `each'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/contextual.rb:20:in `each'
    from org/jruby/RubyEnumerable.java:461:in `to_a'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/criteria/findable.rb:108:in `from_database'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/criteria/findable.rb:76:in `multiple_from_db'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/criteria/findable.rb:20:in `execute_or_raise'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/criteria/findable.rb:41:in `find'
    from vendor/bundle/jruby/2.5.0/gems/mongoid-7.0.4/lib/mongoid/findable.rb:94:in `find'
    from lib/authentication/legacy_token_strategy.rb:34:in `legacy_session'

Session.find(token).uid