anchor.diff:  An externalizer is an implementation of the `org.wildfly.clustering.marshalling.Externalizer` interface, which dictates how a given class should be marshalled.
   An externalizer reads/writes the state of an object directly from/to an input/output stream, but also:
   
  -1. Allows an application to store an object in the session that does not implement `java.io.Serializable`
  -1. Eliminates the need to serialize the class descriptor of an object along with its state
  +. Allows an application to store an object in the session that does not implement `java.io.Serializable`
  +. Eliminates the need to serialize the class descriptor of an object along with its state
   
   e.g.
   [source,java]
  
positive.code: 
  A web application can override the default distributable session management behavior in 1 of 2 ways:
  
  1. Reference a session-management profile by name
  1. Provide deployment-specific session management configuration
  
  === Referencing an existing session management profile
  
  
negative.code: }
  ----
  
  Alternatively, immutable classes can be enumerated via the distributable-web deployment descriptor.
  
  e.g.
  [source,xml]
  ----
  <distributable-web xmlns="urn:jboss:distributable-web:1.0">
      <session-management>
          <immutable-class>foo.bar.ImmutableClass</immutable-class>
          <immutable-class>...</immutable-class>
      </session-management>
  </distributable-web>
  ----
  
  [[session_attribute_marshalling]]
  === Session attribute marshalling
  
  