RFR: 8336588: Ensure Transform downstream receives upstream start items only after downstream started

[Adam Sotona]

On Wed, 17 Jul 2024 21:31:51 GMT, Chen Liang <liach at openjdk.org> wrote:

> There's another bug in ClassFile transform composition where the downstream transform receives items from upstream transform's chained builders before the downstream transform itself starts. This is a simple fix, and a test case against `ClassTransform` is added.

Good catch and fix, thanks.

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Marked as reviewed by asotona (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20227#pullrequestreview-2184970902