Academic employees having continuing appointments and college administrative officers not in a negotiating unit established pursuant to article XIV of the Civil Service Law who have completed at least six consecutive years of service within the university or who, if they previously have had a sabbatical leave, have completed at least six consecutive years of service within the university from the date of return from their last sabbatical leave, shall be eligible for sabbatical leave. In computing consecutive years of service for the purpose of this section, periods of vacation leave and periods of sick leave with salary shall be included; periods of leave of absence, other than vacation and sick leave with salary, and periods of part-time service shall not be included, but shall not be deemed an interruption of otherwise consecutive service.