in src/main/java/com/amazon/sqs/javamessaging/AmazonSQSExtendedClient.java [974:991]
private SendMessageRequest storeMessageInS3(SendMessageRequest sendMessageRequest) {
// Read the content of the message from message body
String messageContentStr = sendMessageRequest.messageBody();
Long messageContentSize = Util.getStringSizeInBytes(messageContentStr);
SendMessageRequest.Builder sendMessageRequestBuilder = sendMessageRequest.toBuilder();
sendMessageRequestBuilder.messageAttributes(
updateMessageAttributePayloadSize(sendMessageRequest.messageAttributes(), messageContentSize));
// Store the message content in S3.
String largeMessagePointer = payloadStore.storeOriginalPayload(messageContentStr);
sendMessageRequestBuilder.messageBody(largeMessagePointer);
return sendMessageRequestBuilder.build();
}