GH-71: Kinesis Adapters: Handle byte[] directly

Fixes spring-projects/spring-integration-aws#71

It isn't correct to call `converter.convert()` in the
`KinesisMessageHandler` if `payload` is already `ByteBuffer` or `byte[]`
On the other hand an application might be interested in the `byte[]`
payload on the consumer side.
The `KinesisMessageDrivenChannelAdapter` must be able to produce
`byte[]` `payload` without any conversion.

* Add logic into `KinesisMessageHandler` to check the `payload` type
before calling `converter.convert()`
* Allow to configure `converter` to `null` for the
`KinesisMessageDrivenChannelAdapter`.
 The body of the consumed record is presented in the `payload` as is -
 `byte[]`
* Add JavaDoc to the `KinesisMessageHandler.setConverter()`

src/main/java/org/springframework/integration/aws/inbound/kinesis/KinesisMessageDrivenChannelAdapter.java

@@ -179,8 +179,12 @@ public class KinesisMessageDrivenChannelAdapter extends MessageProducerSupport i
 		this.streamInitialSequence = streamInitialSequence;
 	}
 
+	/**
+	 * Specify a {@link Converter} to deserialize the {@code byte[]} from record's body.
+	 * Can be {@code null} meaning no deserialization.
+	 * @param converter the {@link Converter} to use or null
+	 */
 	public void setConverter(Converter<byte[], Object> converter) {
-		Assert.notNull(converter, "'converter' must not be null");
 		this.converter = converter;
 	}
 
@@ -840,8 +844,11 @@ public class KinesisMessageDrivenChannelAdapter extends MessageProducerSupport i
 				switch (KinesisMessageDrivenChannelAdapter.this.listenerMode) {
 					case record:
 						for (Record record : records) {
-							Object payload =
-									KinesisMessageDrivenChannelAdapter.this.converter.convert(record.getData().array());
+							Object payload = record.getData().array();
+
+							if (KinesisMessageDrivenChannelAdapter.this.converter != null) {
+								payload = KinesisMessageDrivenChannelAdapter.this.converter.convert((byte[]) payload);
+							}
 							AbstractIntegrationMessageBuilder<Object> messageBuilder = getMessageBuilderFactory()
 									.withPayload(payload)
 									.setHeader(AwsHeaders.STREAM, this.shardOffset.getStream())

src/main/java/org/springframework/integration/aws/outbound/KinesisMessageHandler.java

@@ -85,6 +85,11 @@ public class KinesisMessageHandler extends AbstractMessageHandler {
 		this.asyncHandler = asyncHandler;
 	}
 
+	/**
+	 * Specify a {@link Converter} to serialize {@code payload} to the {@code byte[]}
+	 * if that isn't {@code byte[]} already.
+	 * @param converter the {@link Converter} to use; cannot be null.
+	 */
 	public void setConverter(Converter<Object, byte[]> converter) {
 		Assert.notNull(converter, "'converter' must not be null.");
 		this.converter = converter;
@@ -209,12 +214,29 @@ public class KinesisMessageHandler extends AbstractMessageHandler {
 			partitionKey = this.sequenceNumberExpression.getValue(this.evaluationContext, message, String.class);
 		}
 
+		Object payload = message.getPayload();
+
+		ByteBuffer data;
+
+		if (payload instanceof ByteBuffer) {
+			data = (ByteBuffer) payload;
+		}
+		else {
+			byte[] bytes =
+					payload instanceof byte[]
+							? (byte[]) payload
+							: this.converter.convert(payload);
+
+			data = ByteBuffer.wrap(
+					bytes);
+		}
+
 		return new PutRecordRequest()
 				.withStreamName(stream)
 				.withPartitionKey(partitionKey)
 				.withExplicitHashKey(explicitHashKey)
 				.withSequenceNumberForOrdering(sequenceNumber)
-				.withData(ByteBuffer.wrap(this.converter.convert(message.getPayload())));
+				.withData(data);
 	}
 
 }