Null key for a Map not allowed in JSON (use a converting NullKeySerializer?) on withCreateContainerCmdModifier and withNetwork

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!

Start with the GenericContainer entry points withCreateContainerCmdModifier and withNetwork, then run the reproducer using the shown image, port binding, and network combination. Trace the generated NetworkingConfig and confirm that using both options no longer produces the null-map-key JSON error while each option continues to work independently.