updated interface documentation, added getRelationshipId() to RelationshipBacked interface

spring-data-neo4j/src/main/java/org/springframework/data/graph/core/NodeBacked.java

@@ -50,7 +50,7 @@ public interface NodeBacked extends GraphBacked<Node> {
      * public class Person {
      *     ...
      *     public Friendship knows(Person p) {
-     *         return (Friendship) relateTo(p, Friendship.class, "knows");
+     *         return relateTo(p, Friendship.class, "knows");
      *     }
      *     ...
      * }
@@ -75,8 +75,6 @@ public interface NodeBacked extends GraphBacked<Node> {
 
 
     /**
-     * Get the ID of the entity.
-     *
      * @return underlying node ID, or null if there is no underlying node
      */
     Long getNodeId();
@@ -122,6 +120,14 @@ public interface NodeBacked extends GraphBacked<Node> {
 
 
 
+    /**
+     * Finds the relationship of the specified type, from this entity's underlying node to the target entity's
+     * underlying node.
+     *
+     * @param target            end node of relationship
+     * @param type              type of the sought relationship
+     * @return requested relationship if it was found, null otherwise
+     */
     Relationship getRelationshipTo(NodeBacked target, String type);
 
     /**

spring-data-neo4j/src/main/java/org/springframework/data/graph/core/RelationshipBacked.java

@@ -31,11 +31,17 @@ public interface RelationshipBacked extends GraphBacked<Relationship>{
 
 
     /**
-     * Reify this relationship entity as another relationship backed type. The same underlying relationship will be
+     * Project this relationship entity as another relationship backed type. The same underlying relationship will be
      * used for the new entity.
      *
      * @param targetType type to project to
      * @return new instance of specified type, sharing the same underlying relationship with this entity
      */
     <R extends RelationshipBacked> R projectTo(Class<R> targetType);
+
+
+    /**
+     * @return the id of the underlying relationship or null if there is none
+     */
+    Long getRelationshipId();
 }