Introduce KClass<T>.javaPrimitiveType and KClass<T>.javaObjectType

#KT-6319 Fixed

compiler/testData/codegen/boxWithStdlib/reflection/javaProperties/java.kt

@@ -0,0 +1,58 @@
+import kotlin.reflect.KClass
+
+fun checkPrimitive(clazz: Class<*>, expected: String) {
+    assert (clazz!!.canonicalName == expected) {
+        "clazz name: ${clazz.canonicalName}"
+    }
+}
+
+fun checkPrimitive(kClass: KClass<*>, expected: String) {
+    checkPrimitive(kClass.java, expected)
+}
+
+fun checkObject(clazz: Class<*>, expected: String) {
+    assert (clazz.canonicalName == "$expected") {
+        "clazz should be object, but found: ${clazz!!.canonicalName}"
+    }
+}
+
+fun checkObject(kClass: KClass<*>, expected: String) {
+    checkObject(kClass.java, expected)
+}
+
+fun box(): String {
+    checkPrimitive(Boolean::class.java, "boolean")
+    checkPrimitive(Boolean::class, "boolean")
+
+    checkPrimitive(Char::class.java, "char")
+    checkPrimitive(Char::class, "char")
+
+    checkPrimitive(Byte::class.java, "byte")
+    checkPrimitive(Byte::class, "byte")
+
+    checkPrimitive(Short::class.java, "short")
+    checkPrimitive(Short::class, "short")
+
+    checkPrimitive(Int::class.java, "int")
+    checkPrimitive(Int::class, "int")
+
+    checkPrimitive(Float::class.java, "float")
+    checkPrimitive(Float::class, "float")
+
+    checkPrimitive(Long::class.java, "long")
+    checkPrimitive(Long::class, "long")
+
+    checkPrimitive(Double::class.java, "double")
+    checkPrimitive(Double::class, "double")
+
+    checkObject(String::class.java, "java.lang.String")
+    checkObject(String::class, "java.lang.String")
+
+    checkObject(Nothing::class.java, "java.lang.Void")
+    checkObject(Nothing::class, "java.lang.Void")
+
+    checkObject(java.lang.Void::class.java, "java.lang.Void")
+    checkObject(java.lang.Void::class, "java.lang.Void")
+
+    return "OK"
+}