code: @Test public void getSessionNotExists(){
    HttpServerExchange exchange=new HttpServerExchange(null);
    Batcher<Batch> batcher=mock(Batcher.class);
    Batch batch=mock(Batch.class);
    SessionConfig config=mock(SessionConfig.class);
    String sessionId="session";
    when(config.findSessionId(exchange)).thenReturn(sessionId);
    when(this.manager.findSession(sessionId)).thenReturn(null);
    when(this.manager.getBatcher()).thenReturn(batcher);
    when(batcher.createBatch()).thenReturn(batch);
    io.undertow.server.session.Session sessionAdapter=this.adapter.getSession(exchange,config);
    assertNull(sessionAdapter);
    verify(batch).close();
    verify(batcher,never()).suspendBatch();
  }
  