Fixed wrong annotations for android.os.Parcel, android.content.ComponentName and android.os.Message

Parcel.readString() and Parcel.readStrongBinder() were wrongly annotated to return NotNull. In fact they both can return null and this is often used in Android development.

ComponentName.getClassName() and ComponentName.getPackageName() cannot return null. Also it's not possible to create ComponentName with null packageName or className.

Message.obtain() (all overloaded variants) never return null.