Remove unused inverse field on @Relationship.

The property were never used by the framework and might be misleading.
Although this is a breaking API change, we do not want to confuse developers
with a misleading property.

closes #255

etc/adr/general-discussion.adoc

@@ -67,14 +67,13 @@ Supporting the embedded use case will be solved on the drivers level.
 We provide `@Relationship` for mapping relationships without properties.
 This annotation shall be used for 1:1 and 1:n mappings.
 It provides an attribute to specifiy the name of the relationship.
-When a relationship is mapped on both sides (that is a circular mapping in the domain model from start to endnode and back) the annotation provides the `inverse` attribute to cater the following use case:
 
 [source,java]
 ----
 @Node("User")
 static class UserNode {
 
-	@Relationship(type = "OWNS", inverse = "owner")
+	@Relationship(type = "OWNS")
 	List<BikeNode> bikes;
 }
 
@@ -86,15 +85,6 @@ static class BikeNode {
 }
 ----
 
-Without the inverse that mapping would lead to three relationships:
-
-1. `(user) - [:OWNS] -> (bike)`
-2. `(user) <- [:OWNER] - (bike)`
-3. `(user) <- [:RENTER] - (bike)`
-
-Which is probably not the intended graph.
-Specifying `inverse` removes ambiguity here.
-
 === "Rich" relationships
 
 There should be no means of using a relationship as aggregate root in SDN/RX (like it is today the case with `@RelationshipEntity`).

spring-data-neo4j/src/main/java/org/neo4j/springframework/data/core/schema/Relationship.java

@@ -70,11 +70,6 @@ public @interface Relationship {
 	@AliasFor("value")
 	String type() default "";
 
-	/**
-	 * @return The name of the attribute containing the other end of the relationship.
-	 */
-	String inverse() default "";
-
 	/**
 	 * If {@code direction} is {@link Direction#OUTGOING}, than the attribute annotated with {@link Relationship} will be
 	 * the target node of the relationship and the class containing the annotated attribute will be the start node.

spring-data-neo4j/src/test/java/org/neo4j/springframework/data/core/mapping/Neo4jMappingContextTest.java

@@ -231,7 +231,7 @@ class Neo4jMappingContextTest {
 		@org.springframework.data.annotation.Id @GeneratedValue
 		private long id;
 
-		@Relationship(type = "OWNS", inverse = "owner")
+		@Relationship(type = "OWNS")
 		List<BikeNode> bikes;
 
 		String name;

spring-data-neo4j/src/test/java/org/neo4j/springframework/data/integration/shared/SimilarThing.java

@@ -35,7 +35,7 @@ public class SimilarThing {
 
 	private String name;
 
-	@Relationship(type = "SimilarTo", inverse = "similarOf")
+	@Relationship(type = "SimilarTo")
 	private SimilarThing similar;
 
 	@Relationship(type = "SimilarTo", direction = Relationship.Direction.INCOMING)