The Drools 5 legacy adapter appears to be incomplete. Code snippet taken directly from the referenced class:

    public Agenda getAgenda() {
        throw new UnsupportedOperationException("org.drools.impl.adapters.StatefulKnowledgeSessionAdapter.getAgenda -> TODO");
    }

    public WorkingMemoryEntryPoint getWorkingMemoryEntryPoint(String name) {
        throw new UnsupportedOperationException("org.drools.impl.adapters.StatefulKnowledgeSessionAdapter.getWorkingMemoryEntryPoint -> TODO");
    }

    public Collection<? extends WorkingMemoryEntryPoint> getWorkingMemoryEntryPoints() {
        throw new UnsupportedOperationException("org.drools.impl.adapters.StatefulKnowledgeSessionAdapter.getWorkingMemoryEntryPoints -> TODO");
    }

    public QueryResults getQueryResults(String query, Object... arguments) {
        throw new UnsupportedOperationException("org.drools.impl.adapters.StatefulKnowledgeSessionAdapter.getQueryResults -> TODO");
    }

    public LiveQuery openLiveQuery(String query, Object[] arguments, ViewChangedEventListener listener) {
        throw new UnsupportedOperationException("org.drools.impl.adapters.StatefulKnowledgeSessionAdapter.openLiveQuery -> TODO");
    }