Who is exempt from workers' compensation in NJ?

Can you clarify who exactly is exempt from workers' compensation in the state of New Jersey? Are there specific categories of employees, such as independent contractors or volunteers, who do not qualify for workers' compensation benefits? Is there a specific criteria or set of conditions that need to be met in order for an employee to be considered exempt? Additionally, are there any notable exceptions or exemptions that are unique to the state of New Jersey?