Examines whether an instance of the qualified role type with name
qualifiedRoleTypeName has been registered by the receiver
using qualifier qualifyingObj.
Examines whether an instance of the qualified role type with name
qualifiedRoleTypeName has been registered by the receiver
using qualifier qualifyingObj.
This constructor establishes the roleOf relationship
between the newly created role object and the role player and registers
a particular object as the qualifier.
This interface defines the behavior for managing roles (i.e., switching roles,
checking on role existence, and checking on entity equivalence), which is implemented
by classes ObjectWithRoles and RoleType.