code: public final <T extends Freezable> T get(Class<T> fc) {
      T pojo = getFreezable();
      assert fc.isAssignableFrom(pojo.getClass());
      return pojo;
    }
docs: The FAST path get-POJO as a {@link Freezable} - final method for speed.
  Will (re)build the POJO from the _mem array.  Never returns NULL.  This
  version has more type-checking.
  @return The POJO, probably the cached instance.