= AuthenticationConverter
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Defines an SPI to attempt to convert a Spring _Authentication_ into an Apache Causeway xref:refguide:applib:index/services/user/UserMemento.adoc[UserMemento] .

The _Authentication_ will have already been verified as having been _Authentication#isAuthenticated() authenticated_ .

Implementations should be defined as Spring _Component_ s and added to the _Configuration application context_ either by being _Import imported_ explicitly or implicitly through _ComponentScan_ .

All known converters are checked one by one, but checking stops once one converter has successively converted the _Authentication_ into a xref:refguide:applib:index/services/user/UserMemento.adoc[UserMemento] (in other words, chain-of-responsibility pattern). Use the _javax.annotation.Priority_ annotation to influence the order in which converter implementations are checked.

== API

[source,java]
.AuthenticationConverter.java
----
interface AuthenticationConverter {
  UserMemento convert(Authentication authentication)     // <.>
}
----

<.> xref:#convert_Authentication[convert(Authentication)]
+
--
Attempt to convert a Spring _Authentication_ (which will have been _Authentication#isAuthenticated() authenticated_ ) into a xref:refguide:applib:index/services/user/UserMemento.adoc[UserMemento] .
--

== Members

[#convert_Authentication]
=== convert(Authentication)

Attempt to convert a Spring _Authentication_ (which will have been _Authentication#isAuthenticated() authenticated_ ) into a xref:refguide:applib:index/services/user/UserMemento.adoc[UserMemento] .

There are many different implementations of _Authentication_ , so the implementation should be targeted at a specific implementation.

The framework provides some default implementations for the most common use cases.
