DATAREDIS-508 - Polishing.

Update JavaDoc, remove trailing whitespace and skip cluster tests if cluster not available.

src/main/java/org/springframework/data/redis/connection/lettuce/LettuceClusterConnection.java

@@ -515,7 +515,7 @@ public class LettuceClusterConnection extends LettuceConnection implements Defau
 		return result;
 	}
 
-	/* 
+	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.redis.connection.lettuce.LettuceConnection#switchToPubSub()
 	 */

src/main/java/org/springframework/data/redis/connection/lettuce/LettuceConnection.java

@@ -798,6 +798,11 @@ public class LettuceConnection extends AbstractRedisConnection {
 		}
 	}
 
+	/**
+	 * {@link #close()} the current connection and open a new pub/sub connection to the Redis server.
+	 *
+	 * @return never {@literal null}.
+	 */
 	protected StatefulRedisPubSubConnection<byte[], byte[]> switchToPubSub() {
 
 		close();