Method operator()

internal/message_equality.cc:240–242

struct StructEqualer {
  bool operator()(EquatableStruct lhs, EquatableStruct rhs) const {
    return JsonMapEquals(lhs, rhs);
  }

  template <typename T>
  std::enable_if_t<std::negation_v<std::is_same<EquatableStruct, T>>, bool>