code: public final Binding getPortBinding(final String portName)
              throws IllegalStateException, IllegalArgumentException {
          assertStarted();
  
          final Map<String, List<PortBinding>> ports = info.networkSettings().ports();
          final List<PortBinding> portBindings = ports.get(portName);
          if (portBindings == null || portBindings.isEmpty()) {
              throw new IllegalArgumentException("Unknown port binding: " + portName);
          }
  
          final PortBinding portBinding = portBindings.get(0);
          return ImmutableBinding.builder() //
                  .host(portBinding.hostIp()) //
                  .port(Integer.parseInt(portBinding.hostPort())) //
                  .build();
      }
docs: Returns the host and port information for the given Docker port name.
  
  @param portName
  Docker port name, e.g. '9200/tcp'
  @return the host and port information
  @throws IllegalStateException
  if the container has not been started
  @throws IllegalArgumentException
  the given port name does not exist