No support for specifying any type

Start with openapi_core/unmarshalling/schemas/unmarshallers.py and factories.py, following the traceback through oneOf handling and array items creation. Reproduce the provided schema with an array whose items are {} and verify that validation succeeds without the "schema not type of Schema" error.

Swagger spec:

Query:
  type: object
  required:
    - select
  properties:
    select:
      type: array
      items:
        type: string
    where:
      type: array
      items:
        type: object
        required:
          - name
          - operator
          - value
        properties:
          name:
            type: string
          operator:
            type: string
          value:
            oneOf:
              - type: string
              - type: number
              - type: boolean
              - type: array
                items: {}

It failed to validate array type for value property (other types are validated fine, when array is removed).

Using lib in combination with Falcon, error is:

Traceback (most recent call last):
  File "D:\.venv\lib\site-packages\falcon\api.py", line 242, in __call__
    process_resource(req, resp, resource, params)
  File "D:\.venv\lib\site-packages\my_lib\falcon_svc.py", line 391, in process_resource
    result = validator.validate(openapi_request)
  File "D:\.venv\lib\site-packages\openapi_core\validation\request\validators.py", line 48, in validate
    body, body_errors = self._get_body(request, operation)
  File "D:\.venv\lib\site-packages\openapi_core\validation\request\validators.py", line 174, in _get_body
    body = self._unmarshal(media_type, casted)
  File "D:\.venv\lib\site-packages\openapi_core\validation\request\validators.py", line 221, in _unmarshal
    param_or_media_type, value, context=UnmarshalContext.REQUEST,
  File "D:\.venv\lib\site-packages\openapi_core\validation\validators.py", line 53, in _unmarshal
    return unmarshaller(value)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 181, in __call__
    properties = self._unmarshal_properties(value)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 225, in _unmarshal_properties
    prop)(prop_value)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 146, in __call__
    return list(map(self.items_unmarshaller, value))
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 181, in __call__
    properties = self._unmarshal_properties(value)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 225, in _unmarshal_properties
    prop)(prop_value)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 244, in __call__
    return self.unmarshallers_factory.create(one_of_schema)(value)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 146, in __call__
    return list(map(self.items_unmarshaller, value))
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\unmarshallers.py", line 141, in items_unmarshaller
    return self.unmarshallers_factory.create(self.schema.items)
  File "D:\.venv\lib\site-packages\openapi_core\unmarshalling\schemas\factories.py", line 48, in create
    raise TypeError("schema not type of Schema")
TypeError: schema not type of Schema

Maybe I'm doing something wrong (?!), but not found in OpenAPI documentation any limitation for array in usage with oneOf, so I assume that above spec is valid and issue is definitely in the lib validation.