Method capacity

cpp/src/arrow/util/secure_string.cc:183–183

std::size_t SecureString::length() const { return secret_.length(); }

std::size_t SecureString::capacity() const { return secret_.capacity(); }

std::span<uint8_t> SecureString::as_span() {
  return {reinterpret_cast<uint8_t*>(secret_.data()), secret_.size()};