DATACMNS-1779 - Consider kotlin.Unit a simple type.

kotlin.Unit is now considered a simple type to avoid PersistentEntity creation.

ReflectionUtils.isVoid(…) now encapsulates the check so that calling code doesn't need to check if Kotlin is on the class path.

src/test/java/org/springframework/data/util/ReflectionUtilsUnitTests.java

@@ -17,11 +17,14 @@ package org.springframework.data.util;
 
 import static org.assertj.core.api.Assertions.*;
 
+import kotlin.Unit;
+
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.core.MethodParameter;
 import org.springframework.data.mapping.model.TypeCreatingSyntheticClassKt;
@@ -163,6 +166,15 @@ public class ReflectionUtilsUnitTests {
 		assertThat(ReflectionUtils.isSupportedKotlinClass(TypeCreatingSyntheticClassKt.class)).isFalse();
 	}
 
+	@Test // DATACMNS-1779
+	public void shouldReportIsVoid() {
+
+		assertThat(ReflectionUtils.isVoid(Void.class)).isTrue();
+		assertThat(ReflectionUtils.isVoid(Void.TYPE)).isTrue();
+		assertThat(ReflectionUtils.isVoid(Unit.class)).isTrue();
+		assertThat(ReflectionUtils.isVoid(String.class)).isFalse();
+	}
+
 	static class Sample {
 
 		public String field;