Reflection: deprecate KClass.defaultType

Its semantics were unclear and its javaType was implemented incorrectly (it
should have returned ParameterizedType with star projections for generic type)

compiler/testData/codegen/box/reflection/classes/defaultType.kt

@@ -1,27 +0,0 @@
-// WITH_REFLECT
-
-import kotlin.reflect.defaultType
-import kotlin.reflect.jvm.javaType
-import kotlin.test.assertEquals
-import kotlin.test.assertNotEquals
-
-class Simple
-class Generic<K, V> {
-    fun thiz() = this
-}
-
-fun simple() = Simple()
-fun genericIntString() = Generic<Int, String>()
-
-fun box(): String {
-    assertEquals(Simple::class.java, Simple::class.defaultType.javaType)
-    assertEquals(::simple.returnType, Simple::class.defaultType)
-
-    assertEquals(Generic::class.java, Generic::class.defaultType.javaType)
-    assertEquals(Generic<*, *>::thiz.returnType, Generic::class.defaultType)
-
-    // Generic<Int, String> != Generic<K, V>
-    assertNotEquals(::genericIntString.returnType, Generic::class.defaultType)
-
-    return "OK"
-}

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -11892,12 +11892,6 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 doTest(fileName);
             }
 
-            @TestMetadata("defaultType.kt")
-            public void testDefaultType() throws Exception {
-                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/classes/defaultType.kt");
-                doTest(fileName);
-            }
-
             @TestMetadata("jvmName.kt")
             public void testJvmName() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/classes/jvmName.kt");

core/reflection.jvm/src/kotlin/reflect/KClasses.kt

@@ -54,6 +54,9 @@ val KClass<*>.companionObjectInstance: Any?
  * Returns a type corresponding to the given class with type parameters of that class substituted as the corresponding arguments.
  * For example, for class `MyMap<K, V>` [defaultType] would return the type `MyMap<K, V>`.
  */
+@Deprecated("This function creates a type which rarely makes sense for generic classes. " +
+            "For example, such type can only be used in signatures of members of that class. " +
+            "Use starProjectedType or createType() for clearer semantics.")
 val KClass<*>.defaultType: KType
     get() = KTypeImpl((this as KClassImpl<*>).descriptor.defaultType) { jClass }