def METHOD_NAME(self, obj, field, pytype):
    metadata = field.metadata.get("metadata", {})
    metadata.update(field.metadata)
    # This is in the upcoming release of marshmallow-jsonschema, but not available yet
    if isinstance(field, fields.Dict):
        values = metadata.get("values", None) or field.value_field
        json_schema = {"title": field.attribute or field.data_key or field.name}
        json_schema["type"] = "object"
        if values:
            values.parent = field
        json_schema["additionalProperties"] = self._get_schema_for_field(obj, values) if values else {}
        return json_schema
    return super().METHOD_NAME(obj, field, pytype)