Container from dockerfile won't build over missing file for copy

Dear maintainers

I'm currently using testcontainers 1.14.3

Following instructions from https://www.testcontainers.org/features/creating_images/, the following code won't produce a valid docker image

new ImageFromDockerfile(IMAGE + ":" + RandomStringUtils.randomAlphabetic(15))
						.withFileFromPath(".", dockerfile)
						.withDockerfile(Paths.get("load/Dockerfile"))

Log states

COPY failed: stat /var/lib/docker/tmp/docker-builder795849804/load: no such file or directory

while dockerfile path points to a directory containing ./load

I don't get any message showing that content is sent to docker build context, why .withFileFromPath(".", dockerfile) isn't catching anything?
What am I doing wrong?

Inizia dal punto di ingresso ImageFromDockerfile e dall’esempio documentato creating-images, quindi riproduci la configurazione fornita con withFileFromPath e withDockerfile usando load/Dockerfile. Ispeziona il contesto di build di Docker e conferma che la directory load referenziata sia inclusa; l’issue è completata quando il passaggio COPY riesce e produce un’immagine valida.