src/main/java/org/nustaq/serialization/FSTClazzNameRegistry.java
public void registerClass(Class c,FSTConfiguration conf) {
        if ( getIdFromClazz(c) != Integer.MIN_VALUE ) {
            return;
        }
        registerClassNoLookup(c,null,conf);
    }
public void registerClass(Class c,FSTConfiguration conf) {
        if ( getIdFromClazz(c) != Integer.MIN_VALUE ) {
            return;
        }
        registerClassNoLookup(c,null,conf);
    }
for read => always increase handle (wg. replaceObject)