@Override
        protected List<Integer> process(List<String> strings) {
            List<Integer> ints = new ArrayList<>();
            for (String s : strings) {
                ints.add(s != null ? Integer.parseInt(s) : 0);
            }
            return ints;
        }
Data type-specific extractor to read value from properties.

@param prefix
@param key
@param properties
@return
src/main/java/io/fabric8/maven/docker/config/handler/property/ValueProvider.java