[code-reflection] Integrated: Report no attribute present when extracting attribute value from externalized op

[Paul Sandoz]

On Tue, 18 Jun 2024 20:48:05 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> `ExternalizedOp.extractAttributeValue` is changed to report `null` to the mapping function if no attribute is present in the attribute map (a `null` value is represented by the value `ExternalizedOp.NULL_ATTRIBUTE_VALUE`) . This enables the caller to support a default value when no attribute is present.
> 
> Variable operations (`VarOp`) now correctly support variables with no names when instantiating from an externalized op.

This pull request has now been integrated.

Changeset: 260ce26c
Author:    Paul Sandoz <psandoz at openjdk.org>
URL:       https://git.openjdk.org/babylon/commit/260ce26ce3f09213f185d1637cb6f546ddbbd3e7
Stats:     59 lines in 7 files changed: 30 ins; 2 del; 27 mod

Report no attribute present when extracting attribute value from externalized op

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PR: https://git.openjdk.org/babylon/pull/150