Addresses the regression regarding pool assistance and includes a regression test for `CompletableFuture::get()`, `CompletableFuture::get(timeout, unit)`, and `CompletableFuture::join()`
------------- Commit messages: - Reinstating individual imports - JDK-8369656 - ensure that caller-assistance only occurs if the pool is shared between caller and callee Changes: https://git.openjdk.org/jdk/pull/27800/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27800&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8369656 Stats: 47 lines in 2 files changed: 43 ins; 0 del; 4 mod Patch: https://git.openjdk.org/jdk/pull/27800.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/27800/head:pull/27800 PR: https://git.openjdk.org/jdk/pull/27800
