Custom Python ODB backends - write() support

Is there any support for implementing write() for custom python ODB backends?

I noticed it wasn't in the docs, but tried implementing it like so:

class MyOdbBackend(pygit2.OdbBackend):

    # snip - other OdbBackend methods

   def write(self, oid, data, length, type):
        print(f"writing {oid} {length} type {type}")
        return True

repo = pygit2.Repository()
odb = pygit2.Odb()
odb.add_backend(MyOdbBackend(), 1)
repo.set_odb(odb)

test_blob_id = repo.create_blob(b"hello world\n")
print(repo[test_blob_id].data)

But I get a _pygit2.GitError: TLS backend doesn't support certificate locations on calling repo.create_blob(). The built-in backends seem to work fine.

Start by reproducing the custom MyOdbBackend.write() example and the failure at repo.create_blob(). Read the OdbBackend and add_backend interfaces plus the related documentation to determine whether write() is supported. Done means the behavior is either implemented and verified with this example or clearly documented with the limitation and error cause.