Feature type specific check of global required and highly recommended attributes.

        :param netCDF4.Dataset dataset: An open netCDF dataset

def check_required_attributes(self, dataset):
        '''
        Feature type specific check of global required and highly recommended attributes.

        :param netCDF4.Dataset dataset: An open netCDF dataset
        '''
        results = []
        required_ctx = TestCtx(BaseCheck.HIGH, 'Required Global Attributes for Trajectory dataset')
        required_ctx.assert_true(
            getattr(dataset, 'nodc_template_version', '').lower() == self.valid_templates[0].lower(),
            'nodc_template_version attribute must be {}'.format(self.valid_templates[0])
        )
        required_ctx.assert_true(
            getattr(dataset, 'cdm_data_type', '') == 'Trajectory',
            'cdm_data_type attribute must be set to Trajectory'
        )
        required_ctx.assert_true(
            getattr(dataset, 'featureType', '') == 'trajectory',
            'featureType attribute must be set to trajectory'
        )
        results.append(required_ctx.to_result())
        return results