public Container.ExecResult execInContainer(
        DockerClient dockerClient,
        InspectContainerResponse containerInfo,
        ExecConfig execConfig
    ) throws UnsupportedOperationException, IOException, InterruptedException {
        return execInContainer(dockerClient, containerInfo, StandardCharsets.UTF_8, execConfig);
    }
Run a command inside a running container as a given user, as using "docker exec -u user".
<p>
This functionality is not available on a docker daemon running the older "lxc" execution
driver. At the time of writing, CircleCI was using this driver.
@param dockerClient the {@link DockerClient}
@param containerInfo the container info
@param execConfig the exec configuration
@return the result of execution
@throws IOException if there's an issue communicating with Docker
@throws InterruptedException if the thread waiting for the response is interrupted
@throws UnsupportedOperationException if the docker daemon you're connecting to doesn't support "exec".
core/src/main/java/org/testcontainers/containers/ExecInContainerPattern.java