[jfx17u] RFR: 8280275: JUnit5 tests using Assumptions API fail to compile in some cases

[Kevin Rushforth]

This PR is dependent on #58 so it is in Draft for now. Once #58 is integrated, I will rebase this and submit it, at which time it will be a clean backport, and the diffs will only show the updated test and build changes associated with just this fix.

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Commit messages:
 - 8280275: JUnit5 tests using Assumptions API fail to compile in some cases

Changes: https://git.openjdk.java.net/jfx17u/pull/59/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx17u&pr=59&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280275
  Stats: 6 lines in 2 files changed: 4 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx17u/pull/59.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx17u pull/59/head:pull/59

PR: https://git.openjdk.java.net/jfx17u/pull/59