message: Fix minor const correctness issue
diff: @@ -327,7 +327,7 @@ public:
  return temp;
  }
  - VectorIterator operator+(const uoffset_t &offset) {
  + VectorIterator operator+(const uoffset_t &offset) const {
  return VectorIterator(data_ + offset * IndirectHelper<T>::element_stride, 0);
  }
  