void writeConfig(String name, String contents) {
        try {
            Files.writeString(tempFolder.toPath().resolve(name + ".cfg"), contents);
        }
        catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }
@author Tony Vaagenes
@author gjoranv
@author ollivir
container-core/src/test/java/com/yahoo/container/di/DirConfigSource.java