When is an interface with a default method initialized?

Question

While searching through the Java Language Specification to answer this question, I learned that

Before a class is initialized, its direct superclass m

Answer 1

The instanceKlass.cpp file from the OpenJDK contains the initialization method InstanceKlass::initialize_impl that corresponds to the Detailed Initialization Procedure in the JLS, which is analogously found in the Initialization section in the JVM Spec.

It contains a new step that is not mentioned in the JLS and not in the JVM book that is referred to in the code:

// refer to the JVM book page 47 for description of steps
...

if (this_oop->has_default_methods()) {
  // Step 7.5: initialize any interfaces which have default methods
  for (int i = 0; i < this_oop->local_interfaces()->length(); ++i) {
    Klass* iface = this_oop->local_interfaces()->at(i);
    InstanceKlass* ik = InstanceKlass::cast(iface);
    if (ik->has_default_methods() && ik->should_be_initialized()) {
      ik->initialize(THREAD);
    ....
    }
  }
}

So this initialization has been implemented explicitly as a new Step 7.5. This indicates that this implementation followed some specification, but it seems that the written specification on the website has not been updated accordingly.

EDIT: As a reference, the commit (from October 2012!) where the respective step has been included in the implementation: http://hg.openjdk.java.net/jdk8/build/hotspot/rev/4735d2c84362

EDIT2: Coincidentally, I found this Document about default methods in hotspot which contains an interesting side note at the end:

3.7 Miscellaneous

Because interfaces now have bytecode in them, we must initialize them at the time that an implementing class is initialized.