puppetlabs-postgresql : INSERT table_grant privilege is reported as Illegal value

I am granting the INSERT privilege to a specific user on a specific table using the following code:

        postgresql::server::table_grant { 'INSERT domains of powerdns':

                privilege => 'INSERT',

                table     => 'domains',

                db        => 'powerdns',

                role      => 'powerdns',

        }

but unfortunately it does not work anymore as I get the following error message back from puppet:

Error: Could not retrieve catalog from remote server: Error 500 on SERVER: Server Error: Evaluation Error: Error while evaluating a Resource Statement, Evaluation Error: Error while evaluating a Function Call, Illegal value for $privilege parameter at /etc/puppet/code/environments/production/modules/postgresql/manifests/server/grant.pp:257:20 at /etc/puppet/code/environments/production/modules/postgresql/manifests/server/table_grant.pp:15 on node mynode

It worked fine with version 5.1.0 of this module but the upgrade to version 5.6.0 broke this.

Thank you very much in advance for fixing this.