10 Dec, 12:23
Ireland's John Lacey will referee his first ever RBS 6 Nations match in February, while Alain Rolland is also included in the Elite Panel in what is his last season.
Prior to that, he had made 39 appearances in the Munster jersey having made his debut in September 2001.
The 22-year-old Williams, who was capped by Ireland at Schools and Under-21 levels, has come through the Munster Academy and this season he moves on to a Development contract.
Meanwhile, the start of the new season moves ever closer with the first of the Munster squad, those not involved at Ireland senior or 'A' levels, expected back for the start of pre-season on Monday.
New head coach Tony McGahan arrives back from holidaying in Australia in the middle of next week and Munster's international contingent will report for pre-season training at the start of the third week in July.