Go back to using Unsafe APIs to create instances without constructors.

The attempted fix replaced a warning with a crash. I believe that a
warning is a better developer experience than a crash.

This reverts commit c0639316b1.

moshi/src/main/java/com/squareup/moshi/ClassFactory.java

@@ -34,9 +34,6 @@ abstract class ClassFactory<T> {
   abstract T newInstance() throws
       InvocationTargetException, IllegalAccessException, InstantiationException;
 
-  private static volatile boolean androidChecked = false;
-  private static volatile boolean tryUnsafe = true;
-
   public static <T> ClassFactory<T> get(final Class<?> rawType) {
     // Try to find a no-args constructor. May be any visibility including private.
     try {
@@ -57,20 +54,6 @@ abstract class ClassFactory<T> {
       // No no-args constructor. Fall back to something more magical...
     }
 
-    if (!androidChecked) {
-      try {
-        Class<?> androidBuildClass = Class.forName("android.os.Build$VERSION");
-        Field sdkIntField = androidBuildClass.getDeclaredField("SDK_INT");
-        int sdk = (int) sdkIntField.get(null);
-        if (sdk >= 29) {
-          tryUnsafe = false;
-        }
-      } catch (Exception ignored) {
-      } finally {
-        androidChecked = true;
-      }
-    }
-    if (tryUnsafe) {
     // Try the JVM's Unsafe mechanism.
     // public class Unsafe {
     //   public Object allocateInstance(Class<?> type);
@@ -83,8 +66,7 @@ abstract class ClassFactory<T> {
       final Method allocateInstance = unsafeClass.getMethod("allocateInstance", Class.class);
       return new ClassFactory<T>() {
         @SuppressWarnings("unchecked")
-          @Override
-          public T newInstance() throws InvocationTargetException, IllegalAccessException {
+        @Override public T newInstance() throws InvocationTargetException, IllegalAccessException {
           return (T) allocateInstance.invoke(unsafe, rawType);
         }
         @Override public String toString() {
@@ -96,7 +78,6 @@ abstract class ClassFactory<T> {
     } catch (ClassNotFoundException | NoSuchMethodException | NoSuchFieldException ignored) {
       // Not the expected version of the Oracle Java library!
     }
-    }
 
     // Try (post-Gingerbread) Dalvik/libcore's ObjectStreamClass mechanism.
     // public class ObjectStreamClass {