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

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

    allusers = 'allUsers'
    errors = []
    for acl in acl_list:
        entity = acl.get('entity')
        role = acl.get('role')
        if (entity == allusers):
            ae = make_audit_issue(error_cat, 'ROLE', allusers, role)
            errors.append(ae)
    return errors
