It is hard to discern the actual problem as there are so many "errors" reported in the log file, but it ends with:

[22:47:39.945] [ OK ] AppContentTest.test([apps/PrintEnv.java,apps/dukeplug.png, apps](length=2)); checks=72
[22:47:39.947] [==========] 4 tests ran
[22:47:39.947] [ PASSED ] 3 tests
[22:47:39.948] [ FAILED ] 1 test, listed below
[22:47:39.948] [ FAILED ] AppContentTest.test([apps/PrintEnv.java, dukeplugLink.txt](length=2)); workDir=[test.475efa2b]
[22:47:39.948] 1 FAILED TEST
----------System.err:(66/4569)----------
java.lang.AssertionError: Failed: Check [test.475efa2b/unpacked-dmg/Applications/AppContentTest.app/Contents/Resources/Links/dukeplugLink.txt] path exists
at jdk.jpackage.test.TKit.error(TKit.java:277)
at jdk.jpackage.test.TKit.assertTrue(TKit.java:718)
at jdk.jpackage.test.TKit.assertTrue(TKit.java:705)
at jdk.jpackage.test.TKit.assertPathExists(TKit.java:738)
at jdk.jpackage.test.TKit.assertSymbolicLinkExists(TKit.java:778)
at AppContentTest.lambda$test$0(AppContentTest.java:106)
at jdk.jpackage/jdk.jpackage.internal.util.function.ThrowingConsumer.lambda$toConsumer$0(ThrowingConsumer.java:37)
at jdk.jpackage.test.PackageTest$Handler.lambda$verifyPackageInstalled$2(PackageTest.java:777)
at java.base/java.util.ImmutableCollections$List12.forEach(ImmutableCollections.java:696)
at jdk.jpackage.test.PackageTest$Handler.verifyPackageInstalled(PackageTest.java:777)
at jdk.jpackage.test.PackageTest$Handler.processAction(PackageTest.java:713)
at jdk.jpackage.test.PackageTest$PackageTypePipeline.accept(PackageTest.java:560)
at jdk.jpackage.test.PackageTest$PackageTypePipeline.accept(PackageTest.java:485)
at java.base/java.util.ImmutableCollections$List12.forEach(ImmutableCollections.java:694)
at jdk.jpackage.test.PackageTest.lambda$runActions$1(PackageTest.java:459)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1604)
at jdk.jpackage.test.PackageTest.lambda$runActions$0(PackageTest.java:458)
at java.base/java.lang.Iterable.forEach(Iterable.java:75)
at jdk.jpackage.test.PackageTest.runActions(PackageTest.java:457)
at jdk.jpackage.test.RunnablePackageTest.run(RunnablePackageTest.java:58)
at AppContentTest.test(AppContentTest.java:116)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at jdk.jpackage.test.MethodCall.accept(MethodCall.java:111)
at jdk.jpackage.test.TestInstance.run(TestInstance.java:242)
at jdk.jpackage.test.TKit.lambda$ignoreExceptions$0(TKit.java:154)
at jdk.jpackage.test.TKit.lambda$runTests$1(TKit.java:139)
at java.base/java.util.AbstractList$RandomAccessSpliterator.forEachRemaining(AbstractList.java:722)
at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:803)
at jdk.jpackage.test.TKit.lambda$runTests$0(TKit.java:136)
at jdk.jpackage/jdk.jpackage.internal.util.function.ThrowingRunnable.lambda$toRunnable$0(ThrowingRunnable.java:35)
at jdk.jpackage.test.TKit.withExtraLogStream(TKit.java:123)
at jdk.jpackage.test.TKit.withExtraLogStream(TKit.java:114)
at jdk.jpackage.test.TKit.runTests(TKit.java:135)
at jdk.jpackage.test.Main.runTests(Main.java:121)
at jdk.jpackage.test.Main.lambda$main$5(Main.java:117)
at jdk.jpackage/jdk.jpackage.internal.util.function.ThrowingRunnable.lambda$toRunnable$0(ThrowingRunnable.java:35)
at jdk.jpackage.test.TKit.withExtraLogStream(TKit.java:123)
at jdk.jpackage.test.TKit.withExtraLogStream(TKit.java:114)
at jdk.jpackage.test.Main.main(Main.java:117)
at jdk.jpackage.test.Main.main(Main.java:45)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
at java.base/java.lang.Thread.run(Thread.java:1447)
jdk.jpackage.internal.model.PackagerException: java.nio.file.NoSuchFileException: non-existant
java.nio.file.NoSuchFileException: non-existant
java.lang.RuntimeException: 1 FAILED TEST
at jdk.jpackage.test.Main.reportSummary(Main.java:172)
at jdk.jpackage.test.Main.runTests(Main.java:132)
at jdk.jpackage.test.Main.lambda$main$5(Main.java:117)
at jdk.jpackage/jdk.jpackage.internal.util.function.ThrowingRunnable.lambda$toRunnable$0(ThrowingRunnable.java:35)
at jdk.jpackage.test.TKit.withExtraLogStream(TKit.java:123)
at jdk.jpackage.test.TKit.withExtraLogStream(TKit.java:114)
at jdk.jpackage.test.Main.main(Main.java:117)
at jdk.jpackage.test.Main.main(Main.java:45)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:565)
at com.sun.javatest.regtest.agent.MainWrapper$MainTask.run(MainWrapper.java:138)
at java.base/java.lang.Thread.run(Thread.java:1447)

JavaTest Message: Test threw exception: java.lang.RuntimeException: 1 FAILED TEST
JavaTest Message: shutting down test