Add tests to make sure jpackage emits meaningful error messages when used with invalid app images.
Added `JPackageCommand.nullableOutputBundle()` function that returns an empty `Optional` instance if it fails to deduce a path to the output bundle from jpackage command line. This is the case when jpackage command is used with `--app-image` cli option and referenced app image directory is missing `.jpackage.xml` file. ------------- Commit messages: - 8227529: With malformed --app-image the error messages are awful Changes: https://git.openjdk.org/jdk/pull/16901/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16901&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8227529 Stats: 71 lines in 3 files changed: 64 ins; 0 del; 7 mod Patch: https://git.openjdk.org/jdk/pull/16901.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/16901/head:pull/16901 PR: https://git.openjdk.org/jdk/pull/16901
