Return a json dictionary representing this model.

def _to_dict(self):
        """Return a json dictionary representing this model."""
        _dict = {}
        if hasattr(self, 'document_id') and self.document_id is not None:
            _dict['document_id'] = self.document_id
        if hasattr(self,
                   'configuration_id') and self.configuration_id is not None:
            _dict['configuration_id'] = self.configuration_id
        if hasattr(self, 'status') and self.status is not None:
            _dict['status'] = self.status
        if hasattr(
                self,
                'status_description') and self.status_description is not None:
            _dict['status_description'] = self.status_description
        if hasattr(self, 'filename') and self.filename is not None:
            _dict['filename'] = self.filename
        if hasattr(self, 'file_type') and self.file_type is not None:
            _dict['file_type'] = self.file_type
        if hasattr(self, 'sha1') and self.sha1 is not None:
            _dict['sha1'] = self.sha1
        if hasattr(self, 'notices') and self.notices is not None:
            _dict['notices'] = [x._to_dict() for x in self.notices]
        return _dict