'Looks for Max OWNERS in acl.
return: [list of AuditIssues]'

def _acl_max_owners(self, acl_list, error_cat='ACL'):

    errors = []
    if self.gcp_config.MAX_OWNERS_PER_BUCKET:
        owner = 'OWNER'
        count = 0
        for acl in acl_list:
            role = acl.get('role')
            if (role == owner):
                count += 1
                if (count > self.gcp_config.MAX_OWNERS_PER_BUCKET):
                    ae = make_audit_issue(error_cat, 'MAX', owner)
                    errors.append(ae)
    return errors
