Clear reflection caches in black box codegen tests

To prevent tests from altering outcomes of the subsequent tests.

Also expose the clearCaches method (in the internal class
ReflectionFactoryImpl) so that it can be used in other places in similar
circumstances

core/reflection.jvm/src/kotlin/reflect/jvm/internal/ReflectionFactoryImpl.java

@@ -105,4 +105,11 @@ public class ReflectionFactoryImpl extends ReflectionFactory {
         KDeclarationContainer owner = reference.getOwner();
         return owner instanceof KDeclarationContainerImpl ? ((KDeclarationContainerImpl) owner) : EmptyContainerForLocal.INSTANCE;
     }
+
+    // Misc
+
+    public static void clearCaches() {
+        KClassCacheKt.clearKClassCache();
+        ModuleByClassLoaderKt.clearModuleByClassLoaderCache();
+    }
 }

core/reflection.jvm/src/kotlin/reflect/jvm/internal/kClassCache.kt

@@ -64,3 +64,7 @@ internal fun <T : Any> getOrCreateKotlinClass(jClass: Class<T>): KClassImpl<T> {
     K_CLASS_CACHE = K_CLASS_CACHE.plus(name, WeakReference(newKClass))
     return newKClass
 }
+
+internal fun clearKClassCache() {
+    K_CLASS_CACHE = HashPMap.empty()
+}

core/reflection.jvm/src/kotlin/reflect/jvm/internal/moduleByClassLoader.kt

@@ -41,7 +41,7 @@ private class WeakClassLoaderBox(classLoader: ClassLoader) {
             identityHashCode
 
     override fun toString() =
-            ref.get()?.let { it.toString() } ?: "<null>"
+            ref.get()?.toString() ?: "<null>"
 }
 
 internal fun Class<*>.getOrCreateModule(): RuntimeModuleData {
@@ -70,3 +70,7 @@ internal fun Class<*>.getOrCreateModule(): RuntimeModuleData {
         key.temporaryStrongRef = null
     }
 }
+
+internal fun clearModuleByClassLoaderCache() {
+    moduleByClassLoader.clear()
+}