Usage of `ImageFromDocker` not intuitive if `withDockerfile` is used

When defining a GenericContainer using ImageFromDockerfile like this, the resulting build context will have a very unexpected structure (flattening all files in the build context root?), and building the image will fail if the user is not aware of it.

private final GenericContainer<?> container= new GenericContainer<>(
        new ImageFromDockerfile()
                .withDockerfile(Paths.get("src/main/docker/Dockerfile.jvm"))
                .withFileFromPath("./target", Paths.get("target/"))
);

Start with the ImageFromDockerfile entry point and the withDockerfile and withFileFromPath calls shown in the example. Reproduce the build using src/main/docker/Dockerfile.jvm and target/ to inspect the generated context. Done means the context structure is intuitive and the example builds successfully without requiring undocumented assumptions.