Remove Void wrapper registration in ReflectionUtils

Closes #4048

Author: sbrannen

documentation/src/docs/asciidoc/release-notes/release-notes-5.12.0-M1.adoc

@@ -52,7 +52,6 @@ JUnit repository on GitHub.
 * The `ReflectionSupport.tryToLoadClass(...)` utility methods now support lookups for the
   `"void"` pseudo-type, which indirectly supports `String` to `Class` conversion for
   `"void"` in parameterized tests in JUnit Jupiter.
-* `ReflectionUtils` now treats `Void` as a _wrapper_ type for the `void` pseudo-type.
 * New `addResourceContainerSelectorResolver()` method in
   `EngineDiscoveryRequestResolver.Builder` which supports the discovery of class path
   resource based tests, analogous to the existing `addClassContainerSelectorResolver()`

junit-platform-commons/src/main/java/org/junit/platform/commons/util/ReflectionUtils.java

@@ -263,7 +263,6 @@ public enum HierarchyTraversalMode {
 		primitivesToWrappers.put(long.class, Long.class);
 		primitivesToWrappers.put(float.class, Float.class);
 		primitivesToWrappers.put(double.class, Double.class);
-		primitivesToWrappers.put(void.class, Void.class);
 
 		primitiveToWrapperMap = Collections.unmodifiableMap(primitivesToWrappers);
 	}

platform-tests/src/test/java/org/junit/platform/commons/util/ReflectionUtilsTests.java

@@ -561,7 +561,9 @@ void isAssignableTo() {
 			// Wrappers to Primitives
 			assertTrue(ReflectionUtils.isAssignableTo(Integer.class, int.class));
 			assertTrue(ReflectionUtils.isAssignableTo(Boolean.class, boolean.class));
-			assertTrue(ReflectionUtils.isAssignableTo(Void.class, void.class));
+
+			// Void to void
+			assertFalse(ReflectionUtils.isAssignableTo(Void.class, void.class));
 
 			// Widening Conversions from Wrappers to Primitives
 			assertTrue(ReflectionUtils.isAssignableTo(Integer.class, long.class));