You should work with ByteSource which offers several helper methods:
ByteSource byteSource = Files.asByteSource(new File(...));
Blob blob = blobStore.blobBuilder(name)
.payload(byteSource)
.contentLength(byteSource.size())
.contentMD5(byteSource.hash(Hashing.md5()).asBytes())
.build();
blobStore.putBlob(containerName, blob);
jclouds made these changes to remove functionality duplicated by Guava and make some of the costs of some operations, e.g., hashing, more obvious.