@Override
    public String toString() {
      StringBuilder sb = new StringBuilder("[Landmark: ");
      if (placeId != null) {
        sb.append("placeId=").append(placeId);
      }
      if (displayName != null) {
        sb.append(", displayName=").append(displayName);
      }
      if (types != null && types.length > 0) {
        sb.append(", types=").append(Arrays.toString(types));
      }
      if (spatialRelationship != null) {
        sb.append(", spatialRelationship=").append(spatialRelationship);
      }
      sb.append(", straightLineDistanceMeters=").append(straightLineDistanceMeters);
      sb.append(", travelDistanceMeters=").append(travelDistanceMeters);
      sb.append("]");
      return sb.toString();
    }
The travel distance along the road network between the target location's closest point on a
road, and the landmark's closest access point on a road. This can be unpopulated if the
landmark is disconnected from the road network the target is closest to OR if the target
location was not actually considered to be on the road network.
src/main/java/com/google/maps/model/AddressDescriptor.java