Support models with multi-level hierarchy (via roxspring) (#4503)

* Example of broken multi-level hierarchy

* Support for multiple levels of hierarchy in model objects

* Support for multiple levels of hierarchy in generators

* Regenerated samples

* Temporarily skip scalaz sample verification, which is having issue with Java version in CI container

* Re-enable scalaz in verify samples

Co-authored-by: Rob Oxspring <roxspring@imapmail.org>

samples/client/petstore/perl/t/BigCatTest.t

@@ -0,0 +1,33 @@
+=begin comment
+
+OpenAPI Petstore
+
+This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+
+The version of the OpenAPI document: 1.0.0
+
+Generated by: https://openapi-generator.tech
+
+=end comment
+
+=cut
+
+#
+# NOTE: This class is auto generated by the OpenAPI Generator
+# Please update the test cases below to test the model.
+# Ref: https://openapi-generator.tech
+#
+use Test::More tests => 2;
+use Test::Exception;
+
+use lib 'lib';
+use strict;
+use warnings;
+
+
+use_ok('WWW::OpenAPIClient::Object::BigCat');
+
+my $instance = WWW::OpenAPIClient::Object::BigCat->new();
+
+isa_ok($instance, 'WWW::OpenAPIClient::Object::BigCat');
+