Determines if there is a {@code SecurityManager} instance in the context, and if not, adds 'this' to the
context. This ensures the SubjectFactory instance will have access to a SecurityManager during Subject
construction if necessary.
@param context the subject context data that may contain a SecurityManager instance.
@return The SubjectContext to use to pass to a {@link SubjectFactory} for subject creation.
Determines if there is a {@code SecurityManager} instance in the context, and if not, adds 'this' to the context. This ensures the SubjectFactory instance will have access to a SecurityManager during Subject construction if necessary.
@param context the subject context data that may contain a SecurityManager instance. @return The SubjectContext to use to pass to a {@link SubjectFactory} for subject creation.