private void setSystemProperties()
    {
        systemPropertiesBackup = System.getProperties();
        if (properties != null)
        {
            for (Object o : properties.keySet())
            {
                String key = (String) o;
                String value = properties.getProperty(key);

                System.setProperty(key, value);
                getLog().info("Set property: " + key + " = '" + value + "'");
            }
        }
    }
Plugin properties that are passed to the compiler

@since 1.3.1
protostuff-maven-plugin/src/main/java/io/protostuff/mojo/ProtoCompilerMojo.java