message: null check protection in EnumNet
diff: @@ -9,6 +9,7 @@ package com.frostwire.jlibtorrent;
  import com.frostwire.jlibtorrent.swig.*;
  import java.util.ArrayList;
  +import java.util.Collections;
  import java.util.List;
  /**
  @@ -21,6 +22,10 @@ public final class EnumNet {
  }
  public static List<IpInterface> enumInterfaces(SessionManager session) {
  + if (session.swig() == null) {
  + return Collections.emptyList();
  + }
  +
  ip_interface_vector v = libtorrent.enum_net_interfaces(session.swig());
  int size = (int) v.size();
  ArrayList<IpInterface> l = new ArrayList<>(size);
  @@ -33,6 +38,10 @@ public final class EnumNet {
  }
  public static List<IpRoute> enumRoutes(SessionManager session) {
  + if (session.swig() == null) {
  + return Collections.emptyList();
  + }
  +
  ip_route_vector v = libtorrent.enum_routes(session.swig());
  int size = (int) v.size();
  ArrayList<IpRoute> l = new ArrayList<>(size);
  @@ -45,6 +54,10 @@ public final class EnumNet {
  }
  public static Address defaultGateway(SessionManager session) {
  + if (session.swig() == null) {
  + return new Address();
  + }
  +
  return new Address(libtorrent.get_default_gateway(session.swig()));
  }
  