Update AwsSpringHttpProcessingUtils.java

Now copying single value headers to httpRequest when there are no multi-value headers present in the proxy request

Author: digithead1011

aws-serverless-java-container-springboot3/src/main/java/com/amazonaws/serverless/proxy/spring/AwsSpringHttpProcessingUtils.java

@@ -124,15 +124,19 @@ private static HttpServletRequest generateRequest1(String request, Context lambd
 		populateQueryStringParametersV1(v1Request, httpRequest);
 		populateMultiValueQueryStringParametersV1(v1Request, httpRequest);
 
-		String contentType = null;
-		if (v1Request.getMultiValueHeaders() != null) {
+		final boolean hasSVH = v1Request.getHeaders() != null && !v1Request.getHeaders().isEmpty();
+		final boolean hasMVH = v1Request.getMultiValueHeaders() != null && !v1Request.getMultiValueHeaders().isEmpty();
+		if (hasMVH) {
 			MultiValueMapAdapter headers = new MultiValueMapAdapter(v1Request.getMultiValueHeaders());
 			httpRequest.setHeaders(headers);
-			contentType = v1Request.getMultiValueHeaders().getFirst(HttpHeaders.CONTENT_TYPE);
+		}
+		else if (hasSVH)
+		{
+			v1Request.getHeaders().forEach(httpRequest::addHeader);
 		}
 		populateContentAndContentType(
 			v1Request.getBody(),
-			contentType,
+			httpRequest.getHeader(HttpHeaders.CONTENT_TYPE),
 			v1Request.isBase64Encoded(),
 			httpRequest
 		);