protected void optionallyMapResourceParameterAsVolume(String pathNameInContainer, String resourceLocation) {
        Optional
            .ofNullable(resourceLocation)
            .map(MountableFile::forClasspathResource)
            .ifPresent(mountableFile -> withCopyFileToContainer(mountableFile, pathNameInContainer));
    }
Map (effectively replace) directory in Docker with the content of resourceLocation if resource location is not null

Protected to allow for changing implementation by extending the class

@param pathNameInContainer path in docker
@param resourceLocation    relative classpath to resource
modules/cassandra/src/main/java/org/testcontainers/containers/CassandraContainer.java