[2.1] Custom user provider utilizes an outdated UserInterface Definition

[creativeworkx]

The documentation for CustomUserProvider http://symfony.com/doc/current/cookbook/security/custom_provider.html utilizes an outdated UserInterface Definition (2.0 branch):

Under "Create a User Class" the WebserviceUser class implements the equals function, which in fact was removed from the UserInterface in branch 2.1 and moved to the EquatableInterface

[wouterj]

this is solved in #2111 and this issue can be closed @weaverryan