Custom binary type is ignored, got constructed with external_constructor<value_t::array> instead

[lemonpy]

The binary representation I want to use is std::vector<char> but the following test fails

using json = nlohmann::basic_json<
    std::map,
    std::vector,
    std::string,
    bool,
    std::int64_t,
    std::uint64_t,
    double,
    std::allocator,
    nlohmann::adl_serializer,
    std::vector<char> /* binary_t */>;

TEST_CASE("copy assign binary_t without explicit ctor")
{
    json empty;
    std::vector<char> buf(5, '1');
    empty["buf"] = buf;
    REQUIRE(empty["buf"].is_binary());
}

Instead of using the external_constructor<value_t::binary> I get the external_constructor<value_t::array> .
I tried adding something like !std::is_same<typename BasicJsonType::binary_t::container_type, CompatibleArrayType>::value in the template arguments and works for my case but

===============================================================================
/home/lemon/repos/json_fork/tests/src/unit-bjdata.cpp:208:
TEST CASE:  BJData
  individual values
  binary
  Other Serializations
  No Count No Type

~/repos/json_fork/tests/src/unit-bjdata.cpp:1731: ERROR: CHECK( json::from_bjdata(result) == j_out ) is NOT correct!
  values: CHECK( [120,120,120,120,120,120,120,120,120,120] == {"bytes":[120,120,120,120,120,120,120,120,120,120],"subtype":null} )

~/repos/json_fork/tests/src/unit-bjdata.cpp:1732: ERROR: CHECK( json::from_bjdata(result, true, false) == j_out ) is NOT correct!
  values: CHECK( [120,120,120,120,120,120,120,120,120,120] == {"bytes":[120,120,120,120,120,120,120,120,120,120],"subtype":null} )

===============================================================================
~/repos/json_fork/tests/src/unit-bjdata.cpp:208:
TEST CASE:  BJData
  individual values
  binary
  Other Serializations
  Yes Count No Type

~/repos/json_fork/tests/src/unit-bjdata.cpp:1758: ERROR: CHECK( json::from_bjdata(result) == j_out ) is NOT correct!
  values: CHECK( [120,120,120,120,120,120,120,120,120,120] == {"bytes":[120,120,120,120,120,120,120,120,120,120],"subtype":null} )

~/repos/json_fork/tests/src/unit-bjdata.cpp:1759: ERROR: CHECK( json::from_bjdata(result, true, false) == j_out ) is NOT correct!
  values: CHECK( [120,120,120,120,120,120,120,120,120,120] == {"bytes":[120,120,120,120,120,120,120,120,120,120],"subtype":null} )

===============================================================================
[doctest] test cases:     25 |     24 passed |   1 failed | 0 skipped
[doctest] assertions: 692193 | 691653 passed | 540 failed |
[doctest] Status: FAILURE!

So this BJData is an array by design? Could it be a binary_type_with_subtype?
Thanks