400 Bad Request on Storage.copy

@Capstan

I started seeing this today. Sometimes our integration tests fail with the following error:

ITStorageTest.testCopyBlob:683 » Storage 400 Bad Request
Caused by: com.google.api.client.googleapis.json.GoogleJsonResponseException: 
400 Bad Request
No file found in request.

The code that causes the error is the following:

String sourceBlobName = "test-copy-blob-source";
BlobId source = BlobId.of(BUCKET, sourceBlobName);
ImmutableMap<String, String> metadata = ImmutableMap.of("k", "v");
BlobInfo blob = BlobInfo.builder(source)
    .contentType(CONTENT_TYPE)
    .metadata(metadata)
    .build();
Blob remoteBlob = storage.create(blob, BLOB_BYTE_CONTENT);
assertNotNull(remoteBlob);
String targetBlobName = "test-copy-blob-target";
Storage.CopyRequest req = Storage.CopyRequest.of(source, BlobId.of(BUCKET, targetBlobName));
CopyWriter copyWriter = storage.copy(req); // Exception thrown here

What's weird is that we never experienced this error before today and it does not occur systematically. @Capstan any idea?

For issues like this, the service team finds it super helpful if you can also specify one or more example requests' HTTP log, with request and response headers and body, and any timing information. Scrub the Authorization header or any OAuth token in the request if posting to public fora.