public void add(PortMapping portMapping, String portPropertyFile) {
            if (portPropertyFile != null) {
                toExport.put(portPropertyFile, portMapping.dynamicProperties);
            } else if (globalFile != null) {
                globalExport.putAll(portMapping.dynamicProperties);
            }
        }
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