The anomaly described below happens on jruby-9.3.x. On jruby-9.2.19.0 everything works as expected.

I have a case where an anonymous object implementing java.lang.Iterable is returned from java, but under some circumstances, the Enumerable methods cannot be called on it although Enumerable is one of the ancestors of that object.
Example:

require 'neo4j_ruby_driver'
node = Neo4j::Driver::GraphDatabase.driver('bolt://localhost:7687', Neo4j::Driver::AuthTokens.basic('neo4j', 'pass')) do |driver|
  driver.session do |session|
    session.run('CREATE (t:Test{a: ["a", "b"]}) RETURN t').first.first
  end
end
node.properties # 1st call
require 'active_graph'
node.properties # 2nd call

There is quite a bit of prepending and including of ruby modules into java classes going on in both gems. If the 1st call is made everything looks good. But if the 1st call is commented out the error is:

NoMethodError:
  undefined method `map' for #<Java::OrgNeo4jDriverInternalValue::ListValue::1:0x26f7b114>
  Did you mean?  tap
# /Users/heinrich/mck/neo4j-ruby-driver/jruby/neo4j/driver/ext/ruby_converter.rb:12:in `as_ruby_object'
# /Users/heinrich/mck/neo4j-ruby-driver/jruby/neo4j/driver/ext/map_converter.rb:9:in `to_h'
# ./lib/active_graph/core/entity.rb:7:in `properties'
# ./spec/spec_helper.rb:16:in `<main>'

the caller side looks like this:

values(&:itself).map(&:as_ruby_object)

values(&:itself) returns an object of an anonymous class implementing java.lang.Iterable which has Enumerable as ancestor.

You can call the each method from Iterable and then chain map onto it and this works but that's just a workaround.

I am sorry for this vague description but this is a close as I can get after multiple hours of investigation.
I believe there are 2 problems:

1. Under some conditions the Enumerable methods are erased from anonymous Iterable
2. Some type of caching problem where the methods of the anonymous Iterable depend on the context in which the first instance of the anonymous class has been created.

I'm happy to do further debugging with your guidance, but right now I'm out of ideas. I was not able to create a minimal example to reproduce the issue.