The following specification parts in Byte Code section (ie.
aastore,checkcast,instanceof) define rules to the case
where a referenced object is an interface type.
However, at runtime an referenced object can not be an interface type but a class
type because an object can not be created from an interface (see the definition
of 'new' byte code) but an object can be created from a class.
So, the following specification parts saying about the case of "interface type"
may be not appropriate for runtime behavior.

Any guidance to our licensees about how to implement the speficiation part
would be appreciated.

=== instanceof ===========================================

instanceof
<snip>

 Format

    instanceof
    indexbyte1
    indexbyte2

Forms

    instanceof = 193 (0xc1)

Operand Stack

    ..., objectref ..., result

Description

<snip>

    The following rules are used to determine whether an objectref
    that is not null is an instance of the resolved type: If S is the class of
    the object referred to by objectref and T is the resolved class, array,
    or interface type, instanceof determines whether objectref is an instance
    of T as follows:

<snip>

----------> The following parts are not appropriate.

    * If S is an interface type, then:

          o If T is a class type, then T must be Object (¿2.4.7).

          o If T is an interface type, then T must be the same interface as S,
            or a superinterface of S (¿2.13.2).

=== checkcast ============================================

checkcast

<snip>

    Format

    checkcast
    indexbyte1
    indexbyte2

Forms

    checkcast = 192 (0xc0)

Operand Stack

    ..., objectref ..., objectref

Description

 <snip>

   The following rules are used to determine whether an objectref
   that is not null can be cast to the resolved type: if S is
   the class of the object referred to by objectref and T is
   the resolved class, array, or interface type, checkcast determines
   whether objectref can be cast to type T as follows:

<snip>

----------> The following parts are not appropriate.

    * If S is an interface type, then:

          o If T is a class type, then T must be Object (¿2.4.7).

          o If T is an interface type, then T must be the same interface as S
            or a superinterface of S (¿2.13.2).

=== aastore =============================================

aastore

<snip>

    Format

    aastore

Forms

    aastore = 83 (0x53)

Operand Stack

    ..., arrayref, index, value ...

Description
<snip>

    The type of value must be assignment compatible (¿2.6.7) with
    the type of the components of the array referenced by arrayref.
    Assignment of a value of reference type S (source) to a variable
    of reference type T (target) is allowed only when the type S supports
    all the operations defined on type T. The detailed rules follow:

<snip>

----------> The following parts are not appropriate.

    * If S is an interface type, then:

          o If T is a class type, then T must be Object (¿2.4.7).

          o If T is an interface type, then T must be the same interface
            as S or a superinterface of S (¿2.13.2).

=======================================================