Codegen doesn't support nullable types

失敗は rpdk/java/pojo_resolver.py の _java_property_type にあり、cfn-cli generate から到達します。まずそこから始め、nullable Canceled スキーマで再現してください。["integer", "null"] プロパティの生成が unhashable-list エラーなしで成功すれば完了です。

This is the property that I’m trying to define:

    "Canceled": {
        "description": "POSIX Timestamp of cancellation of this downtime (null if not canceled)",
        "type": ["integer", "null"]
    },

This should be ok according to JsonSchema, but cfn-cli generate fails and rpdk.log contains this:

Traceback (most recent call last):
  File "/Users/.../programming/aws-cloudformation-rpdk-nightly/env/lib/python3.7/site-packages/rpdk/core/cli.py", line 95, in main
    args.command(args)
  File "/Users/.../programming/aws-cloudformation-rpdk-nightly/env/lib/python3.7/site-packages/rpdk/core/generate.py", line 15, in generate
    project.generate()
  File "/Users/.../programming/aws-cloudformation-rpdk-nightly/env/lib/python3.7/site-packages/rpdk/core/project.py", line 190, in generate
    return self._plugin.generate(self)
  File "/Users/.../programming/aws-cloudformation-rpdk-nightly/env/lib/python3.7/site-packages/rpdk/java/codegen.py", line 255, in generate
    pojos = pojo_resolver.resolve_pojos()
  File "/Users/.../programming/aws-cloudformation-rpdk-nightly/env/lib/python3.7/site-packages/rpdk/java/pojo_resolver.py", line 58, in resolve_pojos
    java_property_map[prop_name] = self._java_property_type(prop_schema)
  File "/Users/.../programming/aws-cloudformation-rpdk-nightly/env/lib/python3.7/site-packages/rpdk/java/pojo_resolver.py", line 88, in _java_property_type
    return primitive_types_map[json_type]
TypeError: unhashable type: 'list'