Order of blank node identifiers during normalization #249

Hi, I am working on a project to sign LD documents for which normalisation is an important step. My goal is to use a standard normalisation algorithm across language implementations so that signature verification works.

At present, I am working on Python<>Java compatibility. I have observed some differences between the normalised output of PyLD and jsonld-java, specifically in the order and naming of blank nodes. I'm trying to understand if jsonld-java follows the URDNA2015 normalisation algorithm which is implemented by PyLD

I'm including how I invoke the normalisation using both libraries. If needed, I can share the normalised outputs also.

PyLD Invocation

# normalize a document using the RDF Dataset Normalization Algorithm
# (URDNA2015), see: http://json-ld.github.io/normalization/spec/
normalized = jsonld.normalize(document, options={
    'algorithm': 'URDNA2015',
    'format': 'application/n-quads'
})

# - doc is a dict containing a JSON-LD document.
# - normalized is a string that is a canonical representation of the document
#    that can be used for hashing, comparison, etc.

jsonld-java Invocation

final JsonLdOptions options = new JsonLdOptions();
options.format = JsonLdConsts.APPLICATION_NQUADS;
String normalized = (String)JsonLdProcessor.normalize(document, options);
 
// - document is Map<String, Object> containing a JSON-LD document.
// - normalized is a string that is intended to be used for hashing