DATAREDIS-645 - Polishing.

Migrate LettuceReactiveStringCommandsTests to StepVerifier and replace Collection.stream().toArray(…) with Collection.toArray(…).

Original Pull Request: spring-projects#249

Author: mp911de

src/main/java/org/springframework/data/redis/connection/ReactiveStringCommands.java

@@ -192,7 +192,7 @@ default Mono<Boolean> set(ByteBuffer key, ByteBuffer value, Expiration expiratio
 	 * Get single element stored at {@literal key}.
 	 *
 	 * @param key must not be {@literal null}.
-	 * @return empty {@link ByteBuffer} in case {@literal key} does not exist.
+	 * @return {@link Mono#empty()} in case {@literal key} does not exist.
 	 * @see <a href="http://redis.io/commands/get">Redis Documentation: GET</a>
 	 */
 	default Mono<ByteBuffer> get(ByteBuffer key) {
@@ -218,7 +218,7 @@ default Mono<ByteBuffer> get(ByteBuffer key) {
 	 *
 	 * @param key must not be {@literal null}.
 	 * @param value must not be {@literal null}.
-	 * @return
+	 * @return {@link Mono#empty()} if key did not exist.
 	 * @see <a href="http://redis.io/commands/getset">Redis Documentation: GETSET</a>
 	 */
 	default Mono<ByteBuffer> getSet(ByteBuffer key, ByteBuffer value) {

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

@@ -67,7 +67,7 @@ public Flux<MultiValueResponse<List<ByteBuffer>, ByteBuffer>> mGet(Publisher<Lis
 
 			Assert.notNull(keys, "Keys must not be null!");
 
-			return cmd.mget(keys.stream().toArray(ByteBuffer[]::new)).map((value) -> value.getValueOrElse(EMPTY_BYTE_BUFFER))
+			return cmd.mget(keys.toArray(new ByteBuffer[0])).map((value) -> value.getValueOrElse(EMPTY_BYTE_BUFFER))
 					.collectList().map((values) -> new MultiValueResponse<>(keys, values));
 		}));
 	}
@@ -337,7 +337,7 @@ public Flux<NumericResponse<BitOpCommand, Long>> bitOp(Publisher<BitOpCommand> c
 
 			Mono<Long> result = null;
 			ByteBuffer destinationKey = command.getDestinationKey();
-			ByteBuffer[] sourceKeys = command.getKeys().stream().toArray(ByteBuffer[]::new);
+			ByteBuffer[] sourceKeys = command.getKeys().toArray(new ByteBuffer[0]);
 
 			switch (command.getBitOp()) {
 				case AND:
@@ -369,6 +369,7 @@ public Flux<NumericResponse<BitOpCommand, Long>> bitOp(Publisher<BitOpCommand> c
 	 */
 	@Override
 	public Flux<NumericResponse<KeyCommand, Long>> strLen(Publisher<KeyCommand> commands) {
+
 		return connection.execute(cmd -> {
 
 			return Flux.from(commands).flatMap(command -> {