neutral

The neutral return value for t. An InvocationHandler returning null for a PRIMITIVE return type throws NPE (its own javadoc says so), so this has to be TOTAL over every type the interface can declare — not a ladder that grows a case per MC release. A primitive's neutral value is exactly the JVM's default for a field of that type, read off a fresh one-element array, so there is no table that can go stale (boolean -> false falls out of it, which is why it is no longer written down). void reports isPrimitive == true but has no array type, and a null return for it is ignored by the proxy.