@Override
  public CompletableFuture<List<NatPortMapping>> getPortMappings() {
    checkState(isStarted(), "Cannot call getPortMappings() when in stopped state");
    return CompletableFuture.completedFuture(forwardedPorts);
  }
Returns all known port mappings.

@return The known port mappings wrapped in a {@link java.util.concurrent.Future}.
nat/src/main/java/org/hyperledger/besu/nat/upnp/UpnpNatManager.java