private void updateDynamicProperties(Map<String, ?> dynamicPorts) {
        for (Map.Entry<String, ?> entry : dynamicPorts.entrySet()) {
            String var = entry.getKey();
            String val = entry.getValue().toString();

            projProperties.setProperty(var, val);
            dynamicProperties.setProperty(var, val);
        }
    }
Return the content of the mapping as an array with all specifications as given

@return port mappings as JSON array or null if no mappings exist
src/main/java/io/fabric8/maven/docker/access/PortMapping.java