Array fields in value objects

[John Bossons]

The current version of JEP 401 describes the potential flattening of value
object array elements, but leaves unspecified the treatment of value object
fields that are themselves (immutable) arrays. Some questions:

1) Is a primitive array field (a field that is an array of primitives)
necessarily accessed by reference (like an identity object) or can it be
accessed as a bit vector (like a scalar primitive)?
Example (fixed char array length):
value class PostCodeCA {
    char[] codeValue;  // 6-char code, Ascii letter/number chars, could
store as byte[]
    PostCodeCA(String s) {
    codeValue = s.toCharArray();
    // validation code, inter alia checks length == 6
    }
    ...  // Note that array elements are immutable because private
}
Can a PostCodeCA instance be stored as a bit vector, avoiding the
indirection of a String reference?

2) Can the following be flattened (apart from the inescapable String ref)?
value record AddressCA { String streetAddress, enum provCA, PostCodeCA
zipCode }
Note that use of the PostCodeCA class ensures the zipCode value is
immutable.

3) Does it matter if an array field is of varying length?
Example:
value class CampaignArea {
    int areaID;
    PostCodeCA[] zipCodes;  // varying array length, again immutable
because private
    CampaignArea(int areaID, List<PostCodeCA> zipCodes) { ... }
    ...
}
Does this class definition potentially permit flattening of a CampaignArea
instance?

This isn't just about strings, but they illustrate the issue as well as the
potential. Also, it would be useful if this could be clarified in the JEP
401 text.

John

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