Optional<ContainerState> getContainerByServiceName(String serviceName) {
        String serviceInstantName = getServiceInstanceName(serviceName);
        return Optional.ofNullable(serviceInstanceMap.get(serviceInstantName));
    }
Get the port that an exposed service can be found at, from the host machine
(i.e. should be the machine that's running this Java process).
<p>
The service must have been declared using DockerComposeContainer#withExposedService.

@param serviceName the name of the service as set in the docker-compose.yml file.
@param servicePort the port exposed by the service container.
@return a port that can be used for accessing the service container.
core/src/main/java/org/testcontainers/containers/ComposeDelegate.java