Address comments

Author: davidh44

test/v2-migration-tests/src/test/resources/software/amazon/awssdk/v2migrationtests/maven/after/src/main/java/foo/bar/S3Streaming.java

@@ -60,7 +60,7 @@ void putObject_bucketKeyStreamMetadata(String bucket, String key, InputStream st
 
         HeadObjectResponse metadataWithoutLength = HeadObjectResponse.builder()
             .build();
-        /*AWS SDK for Java v2 migration: When using InputStream to upload with S3Client, Content-Length should be specified and used with RequestBody.fromInputStream(). Otherwise, the entire stream will be buffered in memory.*/s3.putObject(PutObjectRequest.builder().bucket(bucket).key(key).build(), RequestBody.fromContentProvider(() -> stream, "application/octet-stream"));
+        /*AWS SDK for Java v2 migration: When using InputStream to upload with S3Client, Content-Length should be specified and used with RequestBody.fromInputStream(). Otherwise, the entire stream will be buffered in memory. If content length must be unknown, we recommend using the CRT-based S3 client - https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/crt-based-s3-client.html*/s3.putObject(PutObjectRequest.builder().bucket(bucket).key(key).build(), RequestBody.fromContentProvider(() -> stream, "application/octet-stream"));
     }
 
     /**
@@ -92,7 +92,7 @@ void putObject_requestPojoWithInputStream(String bucket, String key) {
 
         PutObjectRequest request1 = PutObjectRequest.builder().bucket(bucket).key(key).websiteRedirectLocation("location")
             .build();
-        /*AWS SDK for Java v2 migration: When using InputStream to upload with S3Client, Content-Length should be specified and used with RequestBody.fromInputStream(). Otherwise, the entire stream will be buffered in memory.*/s3.putObject(request1, RequestBody.fromContentProvider(() -> inputStream1, "application/octet-stream"));
+        /*AWS SDK for Java v2 migration: When using InputStream to upload with S3Client, Content-Length should be specified and used with RequestBody.fromInputStream(). Otherwise, the entire stream will be buffered in memory. If content length must be unknown, we recommend using the CRT-based S3 client - https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/crt-based-s3-client.html*/s3.putObject(request1, RequestBody.fromContentProvider(() -> inputStream1, "application/octet-stream"));
 
         HeadObjectResponse metadata = HeadObjectResponse.builder()
             .build();
@@ -159,4 +159,16 @@ void putObjectRequest_withMetadata() {
             .expires(expiry.toInstant())
             .build();
     }
+
+    void putObjectRequester_emptyMetadata() {
+        HeadObjectResponse emptyMetadata1 = HeadObjectResponse.builder()
+            .build();
+        PutObjectRequest request1 =PutObjectRequest.builder().bucket("bucket").key("key").websiteRedirectLocation("location")
+            .build();
+
+        HeadObjectResponse emptyMetadata2 = HeadObjectResponse.builder()
+            .build();
+        PutObjectRequest request2 = PutObjectRequest.builder().bucket("bucket").key("key").websiteRedirectLocation("location")
+            .build();
+    }
 }

test/v2-migration-tests/src/test/resources/software/amazon/awssdk/v2migrationtests/maven/before/src/main/java/foo/bar/S3Streaming.java

@@ -140,4 +140,13 @@ void putObjectRequest_withMetadata() {
 
         PutObjectRequest request = new PutObjectRequest("bucket", "key", "location").withMetadata(metadata);
     }
+
+    void putObjectRequester_emptyMetadata() {
+        ObjectMetadata emptyMetadata1 = new ObjectMetadata();
+        PutObjectRequest request1 = new PutObjectRequest("bucket", "key", "location").withMetadata(emptyMetadata1);
+
+        ObjectMetadata emptyMetadata2 = new ObjectMetadata();
+        PutObjectRequest request2 = new PutObjectRequest("bucket", "key", "location");
+        request2.setMetadata(emptyMetadata2);
+    }
 }

v2-migration/src/main/java/software/amazon/awssdk/v2migration/S3PutObjectRequestToV2.java

@@ -381,7 +381,7 @@ private J convertSetMetadataToBuilder(J.MethodInvocation method) {
             Map<String, Expression> map = metadataMap.get(metadataName);
             if (map == null) {
                 // should never happen unless user passes in empty ObjectMetadata
-                // remove metadata setter
+                // remove entire line
                 return null;
             }
 
@@ -444,6 +444,7 @@ private J.MethodInvocation saveMetadataValueAndRemoveStatement(J.MethodInvocatio
             map.put(methodName, value);
             metadataMap.put(variableName, map);
 
+            // remove entire line
             return null;
         }
 
@@ -507,7 +508,9 @@ private void addTmImport(String pojoName) {
 
         private List<Comment> inputStreamBufferingWarningComment() {
             String warning = "When using InputStream to upload with S3Client, Content-Length should be specified and used "
-                             + "with RequestBody.fromInputStream(). Otherwise, the entire stream will be buffered in memory.";
+                             + "with RequestBody.fromInputStream(). Otherwise, the entire stream will be buffered in memory. If"
+                             + " content length must be unknown, we recommend using the CRT-based S3 client - "
+                             + "https://docs.aws.amazon.com/sdk-for-java/latest/developer-guide/crt-based-s3-client.html";
             return createComments(warning);
         }
     }