* Will throw an exception if an instance has already been created and is
* not {@link ContextReplacePolicy#REPLACEABLE}.
*/
protected IsisContext(final ContextReplacePolicy replacePolicy, final SessionClosePolicy sessionClosePolicy, final IsisSessionFactory sessionFactory) {
if (singleton != null && !singleton.isContextReplaceable()) {
throw new IsisException("Isis Context already set up and cannot be replaced");
}
singleton = this;
this.sessionFactory = sessionFactory;
this.sessionClosePolicy = sessionClosePolicy;
this.replacePolicy = replacePolicy;