code: public NDArrayDoublesProto.NDArrayDoubles.Builder getProtoBuilder() {
      NDArrayDoublesProto.NDArrayDoubles.Builder b = NDArrayDoublesProto.NDArrayDoubles.newBuilder();
      for (int n : getDimensions()) {
        b.addDimensionSize(n);
      }
      for (double value : values) {
        b.addValues(value);
      }
      return b;
    }
docs: Returns the proto builder object for this feature factor. Recursively constructs protos for all the concat
  vectors in factorTable.
  
  @return proto Builder object