Istio currently supports both SotW and Delta protocol. However, the delta implementation is not yet optimized well, so it performs mostly the same as SotW.

## Controllers

   *
   * <p>To ensure that the created instance obeys its contract, the parameters should satisfy the
   * following constraints. This is the callers responsibility and is not enforced here.
   *
   * <ul>
   *   <li>Both {@code xStats} and {@code yStats} must have the same {@code count}.
   *   <li>If that {@code count} is 1, {@code sumOfProductsOfDeltas} must be exactly 0.0.

new properties on a task, extension or domain object that use plain getters and setters.  It is also not acceptable to add setters that take a Provider.

Note that when adding a lazy property to an existing class, you need to check if instances of the class are instantiated via ObjectFactory. Most classes are instantiated this way, but it's possible that a class without any lazy properties was never updated to use it. A tell-tale sign that an object is not instantiated via the ObjectFactory...

A non-current object version is a version which is not the latest for a given object. It is possible to set up an automatic removal of non-current versions when a version becomes older than a given number of days.

e.g., To scan objects stored under `user-uploads/` prefix and remove versions older than one year.

```
{
    "Rules": [
        {
            "ID": "Removing all old versions",
            "Filter": {

      /*
       * 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 {

	case w.ch <- buf:
		return len(p), nil
	case <-w.ctx.Done():
		return 0, context.Cause(w.ctx)
	}
}

// WriterToChannel will return an io.Writer that writes to the given channel.
// The context both allows returning errors on writes and to ensure that
// this isn't abandoned if the channel is no longer being read from.
func WriterToChannel(ctx context.Context, ch chan<- []byte) io.Writer {

 * be primitive. If this annotation is applied to methods with zero parameters, or more than one
 * parameter, the object containing the method will not be able to register for event delivery from
 * the {@link EventBus}.
 *
 * <p>Unless also annotated with @{@link AllowConcurrentEvents}, event subscriber methods will be
 * invoked serially by each event bus that they are registered with.
 *
 * @author Cliff Biffle
 * @since 10.0
 */

  //
  // The value of this field can be more than 100, implying that this
  // priority level can borrow a number of seats that is greater than
  // its own nominal concurrency limit (NominalCL).
  // When this field is left `nil`, the limit is effectively infinite.
  // +optional
  optional int32 borrowingLimitPercent = 4;
}

// NonResourcePolicyRule is a predicate that matches non-resource requests according to their verb and the

  //
  // The value of this field can be more than 100, implying that this
  // priority level can borrow a number of seats that is greater than
  // its own nominal concurrency limit (NominalCL).
  // When this field is left `nil`, the limit is effectively infinite.
  // +optional
  optional int32 borrowingLimitPercent = 4;
}

// NonResourcePolicyRule is a predicate that matches non-resource requests according to their verb and the

But that's not the only way to declare dependencies (although it would probably be the more common).

The key factor is that a dependency should be a "callable".

A "**callable**" in Python is anything that Python can "call" like a function.

So, if you have an object `something` (that might _not_ be a function) and you can "call" it (execute it) like:

```Python
something()
```

or

```Python