DATAMONGO-577 - Cleaned up obsolete property.

The version property in BasicMongoPersistentEntity became obsolete after the upgrade in Spring Data Commons.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/BasicMongoPersistentEntity.java

@@ -45,8 +45,6 @@ public class BasicMongoPersistentEntity<T> extends BasicPersistentEntity<T, Mong
 	private final SpelExpressionParser parser;
 	private final StandardEvaluationContext context;
 
-	private MongoPersistentProperty versionProperty;
-
 	/**
 	 * Creates a new {@link BasicMongoPersistentEntity} with the given {@link TypeInformation}. Will default the
 	 * collection name to the entities simple type name.