Support Spying and Mocking HashMaps on JDK 16+

[aSemy]

The tests in HashMapMockTest.kt fail on more recent (16+) JDK versions.

mockk/mockk/jvm/src/test/kotlin/io/mockk/jvm/HashMapMockTest.kt

Lines 36 to 43 in 02a6d45

	@Test
	@Disabled("Does not work anymore with jdk 16+")
	fun concurrentHashMap_shouldBeSpied_Successfully() {
	val map = spyk(ConcurrentHashMap<String, String>())
	assertDoesNotThrow { map.put("key", "value") }
	verify(exactly = 1) { map.put("key", "value") }
	}

https://github.com/mockk/mockk/runs/7519107510?check_suite_focus=true#step:7:393

HashMapMockTest > concurrentHashMap_shouldBeSpied_Successfully() FAILED
    java.lang.IllegalAccessException: class io.mockk.impl.InternalPlatform cannot access a member of class java.util.concurrent.ConcurrentHashMap (in module java.base) with modifiers "transient volatile"
        at java.base/jdk.internal.reflect.Reflection.newIllegalAccessException(Reflection.java:[392])
        at java.base/java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:674)
        at java.base/java.lang.reflect.Field.checkAccess(Field.java:1102)
        at java.base/java.lang.reflect.Field.get(Field.java:423)
        at io.mockk.impl.InternalPlatform.copyFields$copy(InternalPlatform.kt:114)
        at io.mockk.impl.InternalPlatform.copyFields(InternalPlatform.kt:121)
        at io.mockk.impl.instantiation.AbstractMockFactory.spyk(AbstractMockFactory.kt:107)
        at io.mockk.jvm.HashMapMockTest.concurrentHashMap_shouldBeSpied_Successfully(HashMapMockTest.kt:126)

This was discovered in #444 (comment) and #829.

For now, so I can make progress on #863, I've disabled the tests on JDK16+. I'm making this issue to link in the source code.

[stale]

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[omerates760]

@aSemy Hi, The problem continues. Is there an update?