docs: public AdvancedExternalizer get(Class key) {
        final Class[] keys = this.keys;
        final int mask = keys.length - 1;
        int hc = System.identityHashCode(key) & mask;
        Class k;
        for (;;) {
           k = keys[hc];
           if (k == key) {
              return values[hc];
           }
           if (k == null) {
              // not found
              return null;
           }
           hc = (hc + 1) & mask;
        }
     }