in cxx/fbjni/detail/SimpleFixedString.h [197:203]
constexpr SimpleFixedString(
const That& that,
std::size_t size,
std::index_sequence<Is...>,
std::size_t pos = 0,
std::size_t count = static_cast<std::size_t>(-1)) noexcept
: data_{(Is < (size - pos) && Is < count ? that[Is + pos] : '\0')..., '\0'},