I was using GenericContainer below and encounter issue

Caused by: org.testcontainers.shaded.com.fasterxml.jackson.databind.JsonMappingException: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?) (through reference chain: org.testcontainers.shaded.com.github.dockerjava.core.command.CreateContainerCmdImpl["NetworkingConfig"]->org.testcontainers.shaded.com.github.dockerjava.core.command.CreateContainerCmdImpl$NetworkingConfig["EndpointsConfig"])

GenericContainer<?> xContainer = new GenericContainer<>("x:latest")
  .withExposedPorts(8080)
  .withCreateContainerCmdModifier(cmd -> cmd.withHostConfig(
    new HostConfig().withPortBindings(new PortBinding(Ports.Binding.bindPort(8080), new ExposedPort(8081)))
  ))
  .withNetwork(network);

further investigation shows that the error exists only when withCreateContainerCmdModifier and withNetwork are used at the same time. If they are used without the other it works. But I need both of them one for mapping to a new port and the other one for networking capabilities. Please advice. Thanks!