#### §2.4.1.(c) Duplicate role runtime check

If it cannot be syntactically derived, that the argument to a lifting constructor is a freshly created base object (b), a compile time warning will signal that an additional runtime check is needed: It must be prevented that a new role is created for a base object, which already has a role of the required type in the given team. It is not possible to replace an existing role by use of the lifting constructor. At runtime, any attempt to do so will cause a `org.objectteams.DuplicateRoleException` to be thrown. This exception can only occur in situations where the mentioned compile time warning had been issued.
§6.1 will introduce reflective functions which can be used to manually prevent errors like a duplicate role.