Classic implementations for Application Factories

Adds additional functionality while maintaining backwards compatibility

docs/how-to-adapt.md

@@ -3,6 +3,63 @@
 ## How to adapt
 When you are familiar with using fflib-apex-common, then you need to be aware of a few differences that you will encounter when adopting this extension package.
 
+### Contents
+
+1. [The Application class](#changes-to-the-application)
+1. [Domain class changes](#changes-to-the-domain)
+
+### Changes to the Application
+The factories in the fflib_Application are replaced by an interface structure. 
+To use the backwards compatible version of the factories, change your Application class into the example below.
+Pay special attention to the interface types and implementation classes of the factories. 
+
+```apex
+public class Application
+{
+    public static final fflib_IUnitOfWorkFactory UnitOfWork =
+            new fflib_ClassicUnitOfWorkFactory(
+                    new List<SObjectType>
+                    {
+                            Schema.Account.SObjectType,
+                            Schema.Contact.SObjectType,
+                            ...
+                    }
+            );
+
+    public static final fflib_IServiceFactory Service =
+            new fflib_ClassicServiceFactory(
+                    new Map<Type, Type>
+                    {
+                            IAccountsService.class => AccountsServiceImpl.class,
+                            IContactsService.class => ContactsServiceImpl.class,
+                            ...
+                    }
+            );
+
+    public static final fflib_ISelectorFactory Selector =
+            new fflib_ClassicSelectorFactory(
+                    new Map<SObjectType, Type>
+                    {
+                            Schema.Account.SObjectType => AccountsSelector.class,
+                            Schema.Contact.SObjectType => ContactsSelector.class,
+                            ...
+                    }
+            );
+
+    public static final fflib_IDomainFactory Domain =
+            new fflib_ClassicDomainFactory(
+                    Application.Selector,
+                    new Map<SObjectType, Type>
+                    {
+                            Schema.Account.SObjectType => Accounts.Constructor.class,
+                            Schema.Contact.SObjectType => Contacts.Constructor.class,
+                            ...
+                    }
+            );
+}
+```
+
+
 ### Changes to the domain
 A Domain class is extended from the domain class `SObjects` instead of `fflib_SObjects`.