public static void setStrictRegistration( boolean b ) {
        strictRegistration = b;
    }
When set to true, classes that do not have intrinsic IDs in their
 {@code @Serializable } will not be auto-registered during write.  Defaults
 to true since this is almost never desired behavior with the way
 this code works.  Set to false to get the old permissive behavior.
jme3-networking/src/main/java/com/jme3/network/serializing/Serializer.java