Change order of argument for createPayload

Expecting data first and metadata second aligns better with the single
arg variant that accepts data. This is also consistent with the
RSocket API in the create methods of ByteBufPayload and DefaultPayload.

Author: rstoyanchev

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultRSocketRequester.java

@@ -235,7 +235,7 @@ private Payload firstPayload(DataBuffer data) {
 				DataBufferUtils.release(data);
 				throw ex;
 			}
-			return PayloadUtils.createPayload(metadata, data);
+			return PayloadUtils.createPayload(data, metadata);
 		}
 
 		private Mono<Payload> emptyPayload() {

spring-messaging/src/main/java/org/springframework/messaging/rsocket/DefaultRSocketRequesterBuilder.java

@@ -202,7 +202,7 @@ private Payload getSetupPayload(MimeType dataMimeType, RSocketStrategies strateg
 		}
 		metadata = metadata != null ? metadata : emptyBuffer(strategies);
 		data = data != null ? data : emptyBuffer(strategies);
-		return PayloadUtils.createPayload(metadata, data);
+		return PayloadUtils.createPayload(data, metadata);
 	}
 
 	private DataBuffer emptyBuffer(RSocketStrategies strategies) {

spring-messaging/src/main/java/org/springframework/messaging/rsocket/PayloadUtils.java

@@ -72,11 +72,11 @@ public static DataBuffer retainDataAndReleasePayload(Payload payload, DataBuffer
 	 * or using {@link Unpooled#wrappedBuffer(ByteBuffer...)} if necessary.
 	 * Otherwise, if both are {@link DefaultDataBuffer}, then
 	 * {@link DefaultPayload} is created.
-	 * @param metadata the metadata part for the payload
 	 * @param data the data part for the payload
+	 * @param metadata the metadata part for the payload
 	 * @return the created payload
 	 */
-	public static Payload createPayload(DataBuffer metadata, DataBuffer data) {
+	public static Payload createPayload(DataBuffer data, DataBuffer metadata) {
 		return data instanceof NettyDataBuffer || metadata instanceof NettyDataBuffer ?
 				ByteBufPayload.create(asByteBuf(data), asByteBuf(metadata)) :
 				DefaultPayload.create(asByteBuffer(data), asByteBuffer(metadata));

spring-messaging/src/test/java/org/springframework/messaging/rsocket/DefaultMetadataExtractorTests.java

@@ -163,7 +163,7 @@ public void noDecoder() {
 
 
 	private Payload createPayload(DataBuffer metadata) {
-		return PayloadUtils.createPayload(metadata, this.strategies.dataBufferFactory().allocateBuffer());
+		return PayloadUtils.createPayload(this.strategies.dataBufferFactory().allocateBuffer(), metadata);
 	}
 
 }

spring-messaging/src/test/java/org/springframework/messaging/rsocket/PayloadUtilsTests.java

@@ -81,7 +81,7 @@ public void createWithNettyBuffers() {
 		NettyDataBuffer data = createNettyDataBuffer("sample data");
 		NettyDataBuffer metadata = createNettyDataBuffer("sample metadata");
 
-		Payload payload = PayloadUtils.createPayload(metadata, data);
+		Payload payload = PayloadUtils.createPayload(data, metadata);
 		try {
 			assertThat(payload).isInstanceOf(ByteBufPayload.class);
 			assertThat(payload.data()).isSameAs(data.getNativeBuffer());
@@ -96,7 +96,7 @@ public void createWithNettyBuffers() {
 	public void createWithDefaultBuffers() {
 		DataBuffer data = createDefaultDataBuffer("sample data");
 		DataBuffer metadata = createDefaultDataBuffer("sample metadata");
-		Payload payload = PayloadUtils.createPayload(metadata, data);
+		Payload payload = PayloadUtils.createPayload(data, metadata);
 
 		assertThat(payload).isInstanceOf(DefaultPayload.class);
 		assertThat(payload.getDataUtf8()).isEqualTo(dataBufferToString(data));
@@ -107,7 +107,7 @@ public void createWithDefaultBuffers() {
 	public void createWithNettyAndDefaultBuffers() {
 		NettyDataBuffer data = createNettyDataBuffer("sample data");
 		DefaultDataBuffer metadata = createDefaultDataBuffer("sample metadata");
-		Payload payload = PayloadUtils.createPayload(metadata, data);
+		Payload payload = PayloadUtils.createPayload(data, metadata);
 		try {
 			assertThat(payload).isInstanceOf(ByteBufPayload.class);
 			assertThat(payload.data()).isSameAs(data.getNativeBuffer());
@@ -122,7 +122,7 @@ public void createWithNettyAndDefaultBuffers() {
 	public void createWithDefaultAndNettyBuffers() {
 		DefaultDataBuffer data = createDefaultDataBuffer("sample data");
 		NettyDataBuffer metadata = createNettyDataBuffer("sample metadata");
-		Payload payload = PayloadUtils.createPayload(metadata, data);
+		Payload payload = PayloadUtils.createPayload(data, metadata);
 		try {
 			assertThat(payload).isInstanceOf(ByteBufPayload.class);
 			assertThat(payload.getDataUtf8()).isEqualTo(dataBufferToString(data));