code: @NullableDecl
    private Method getFinalizeReferentMethod() {
      Class<?> finalizableReferenceClass = finalizableReferenceClassReference.get();
      if (finalizableReferenceClass == null) {
        /*
         * FinalizableReference's class loader was reclaimed. While there's a chance that other
         * finalizable references could be enqueued subsequently (at which point the class loader
         * would be resurrected by virtue of us having a strong reference to it), we should pretty
         * much just shut down and make sure we don't keep it alive any longer than necessary.
         */
        return null;
      }
      try {
        return finalizableReferenceClass.getMethod("finalizeReferent");
      } catch (NoSuchMethodException e) {
        throw new AssertionError(e);
      }
    }
docs: Looks up FinalizableReference.finalizeReferent() method.