in rcomp-kafka/src/main/java/org/apache/karaf/rcomp/kafka/ConfigMapper.java [86:92]
private void process(String key, String defaultValue) {
String value = (String)confSource.get(key);
String usedValue = (value != null) ? value : defaultValue;
if (usedValue != null) {
config.put(key, usedValue);
}
}