anchor.diff:  if available, and is re-used to set the content dispostion attachment filename 
   on subsequent GET requests 
   
  -=== Property Resources
  -
  -Property Resources are associated with the properties of Spring Data Entities, that themselves maybe Spring Data Entities.
  -This allows many Resources to be associated with a single Entity.
  -
  -Consider the following `Entity` model, with `Repository` and `Store` interfaces:
  +=== Multiple Content Properties
  +
  +By correlating (i.e. using a common prefix for) the field names of the Spring Content annotations it is possible to associate multiple Spring Resources with a single Entity:-
   
   ====
   [source, java]
   ----
   @Entity
  +@Data
   public class Dvd {
   	private @Id @GeneratedValue Long id;
   	private String title;
   
  -	@OneToOne(cascade = CascadeType.ALL)
  -	@JoinColumn(name = "image_id")
  -	private Image image;
  +	// Content property 'video' storing the DVD video content
  +	private @ContentId UUID videoId;  	
  +	private @ContentLength Long videoLen;	
  +	private @MimeType videoType;
  +
  +	// Content property 'image' storing the Dvd's image
  +	private @ContentId UUID imageId;  	
  +	private @ContentLength Long imageLen;	
  +	private @MimeType imageType;
   	
  -	@OneToOne(cascade = CascadeType.ALL)
  -	@JoinColumn(name = "stream_id")
  -	private Stream stream;
  -	
   	...
   }
  -
  +----
  +====  
  +
  +Spring Content REST will export these two associated Spring Resources to the URI `/dvds/{id}/video` and `/dvds/{id}/image`. 
  +
  +=== Nested Properties
  +
  +With its `@Embeddable`/`@Embedded` annotations JPA along with some of the newer database technologies like Mongo it is possible to model Entities as complex objects.  It may be appropriate to associate Spring Resources as nested properties on these complex objects, as in the following example:-
  +
  +====
  +[source, java]
  +----
   @Entity
  -public class Image {
  -	// Spring Data managed attribute
  +@Data
  +public class Book {
   	private @Id @GeneratedValue Long id;
  -
  -	@OneToOne
  -	private Dvd dvd;
  -
  -	// Spring Content managed attributes
  +	private String title;
  +
  +	private @ContentId UUID coverId;  	
  +	private @ContentLength Long coverLen;	
  +	private @MimeType coverType;
  +
  +	private Chapter chapterOne = new Chapter();
  +	private Chapter chapterTwo = new Chapter();
  +	...
  +}
  +
  +@Embeddable
  +@Data
  +public class Chapter {
  +
  +	// Content property 'video' storing the DVD video content
   	private @ContentId UUID contentId;  	
   	private @ContentLength Long contentLen;	
  +	private @MimeType contentType;
   }
  -
  -@Entity
  -public class Stream {
  -	// Spring Data managed attribute
  -	private @Id @GeneratedValue Long id;
  -
  -	@OneToOne
  -	private Dvd dvd;
  -
  -	// Spring Content managed attributes
  -	private @ContentId UUID contentId;  	
  -	private @ContentLength Long contentLen;	
  -}
  -
  -public interface DvdRepository extends CrudRepository<Dvd, Long> {}
  -
  -public interface ImageStore extends ContentStore<Image, UUID> {}
  -
  -public interface StreamStore extends ContentStore<Stream, UUID> {}
  -----
  -====  
  -
  -In this example separate Resources are associated with the `image` and `stream` properties of the `Dvd` Entity.
  -
  -When using JPA and its relational characteristics these associations are typically (but not always) also Entity
  -associations as well, as shown here.  However when using NoSQL databases like MongoDB that are capable of storing
  -hierarchical data they are true property associations.
  -
  -As before, Spring Data REST will export an item resource under the URI `/dvds/{id}`.  However, this time Spring Content
  -REST will export Property Resources to the URI `/dvds/{id}/image/{contentId}` and `/dvds/{id}/stream/{contentId}`
  -managed by the respective Store.  A property can be set by POSTing to `/dvds/{id}/image` (or `/dvds/{id}/stream`).
  -
  -NOTE: as these properties are both single values these Resources are also available under the simplified URI
  -`/dvds/{id}/image` and `/dvds/{id}/stream` where the `{contentId}` is omitted for convenience.
  -
  -=== Property Collection Resources
  -
  -Property Resources can also target Collections.
  -
  -Consider the following example:-
  -
  -====
  -[source, java]
  -----
  -@Entity
  -public class Dvd {
  -	private @Id @GeneratedValue Long id;
  -	private String title;
  -
  -	@OneToMany
  -	@JoinColumn(name = "chapter_id")
  -	private List<Chapter> chapters;
  -
  -	...
  -}
  -
  -@Entity
  -public class Chapter {
  -	// Spring Data managed attribute
  -	private @Id @GeneratedValue Long id;
  -
  -	// Spring Content managed attributes
  -	private @ContentId UUID contentId;  	
  -	private @ContentLength Long contentLen;	
  -}
  -
  -public interface DvdRepository extends CrudRepository<Dvd, Long> {}
  -
  -public interface ChapterStore extends ContentStore<Chapter, UUID> {}
  -----
  -====
  -
  -In this example many Resources can be associated with the `chapters` property of the `Dvd` Entity.
  -
  -As with Property Resources, Property Collection Resources are also exported to the URI `/dvds/{id}/chapters`.
  -However, in this case, POSTing to `/dvds/{id}/chapters` always *appends* a new Resource to the 'Chapters' Collection.
  -This Resource supports both POST and PUT HTTP methods.
  +----
  +====
  +
  +Spring Content REST will export these associated Spring Resources under the URIs; `/books/{id}/cover`, `/books/{id}/chapterOne/content` and `/books/{id}/chapterTwo/content` and so on.
   
   === Search
   
  
positive.code: ====
    
  In this example a single Spring Resource (the DVD's video stream) is associated with a Dvd Entity by annotating additional
  fields on the Entity using the `@ContentId`, `@ContentLength` and `@MimeType` annotations.   In this example Spring Data
  REST exports a collection  resource to `/dvds`.  The path is derived from the uncapitalized, pluralized, simple class
  name of the domain class.  Item resources are also exported to the URI `/dvds/{id}`.  The HTTP methods used to request
  this endpoint map onto the methods of `CrudRepository`.
  
  Similarly, Spring Content REST also exports any associated Spring Resources to the URI `/dvds/{id}`.  In this case the
  HTTP methods map onto the methods of `ContentStore` as follows:-
  
  - GET -> getContent
  - POST/PUT -> setContent
  - DELETE -> unsetContent
  
negative.code: 
  The following describes typical store scenarios and how they are exported with Spring Content REST.
  
  === Store Resources
  
  Spring Content `Store` manages Spring Resources that, when exported using Spring Content REST, are accessible by REST
  endpoint.
  
  Consider the following Store interface:
  