Subgraph support for GLVs

[GumpacG]

Description

Brings gremlin-javascript, gremlin-dotnet, and gremlin-go to feature parity with gremlin-python for the GraphBinary 4.0 Graph type (0x10), so that g.X().subgraph('sg').cap('sg').next() from any of the four GLVs returns a usable Graph data container instead of throwing an unknown-type error.

Added unit tests and feature tests.

Assisted-by: Devin: Claude Opus 4.7

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.28%. Comparing base (cfd6889) to head (4355bc0).
⚠️ Report is 1063 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3428      +/-   ##
============================================
- Coverage     77.87%   76.28%   -1.59%     
+ Complexity    13578    13516      -62     
============================================
  Files          1015     1017       +2     
  Lines         59308    60919    +1611     
  Branches       6835     7129     +294     
============================================
+ Hits          46184    46471     +287     
- Misses        10817    11651     +834     
- Partials       2307     2797     +490     

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[spmallette]

I think we need to mention python here too? it's essentially all the GLVs being announced for the first time. when i did python i don't think i added any docs because i knew all these other ones had to land too.

i also think this doesn't read like Upgrade Documentation. It should be doing more to explain the relevance of this feature and less about technical details and minutiae.

[GumpacG]

I've changed it to mention that all GLVs support subgraphs and took out the technical details. Thanks!

[kenhuuu]

What does subgraph("sg").cap("sg").asString() return? I noticed that you made a change to what the string output of the Graph is and I'm wondering if it impacts this step. Are there tests for this?

[Cole-Greer]

VOTE +1

[GumpacG]

What does subgraph("sg").cap("sg").asString() return? I noticed that you made a change to what the string output of the Graph is and I'm wondering if it impacts this step. Are there tests for this?

asString() is untouched and should remain the same. I added a feature test for this. I just corrected toString() for GLVs as it used to return "graph[]".

[kenhuuu]

What does subgraph("sg").cap("sg").asString() return? I noticed that you made a change to what the string output of the Graph is and I'm wondering if it impacts this step. Are there tests for this?

asString() is untouched and should remain the same. I added a feature test for this. I just corrected toString() for GLVs as it used to return "graph[]".

Yea, there's still something a bit odd about this to me but I guess its comes down again to the fact that Java has more capabilities than the other GLVs. The deserializer in Java actually turns the Graph into a TinkerGraph so the toString() and asString() match, but you don't have this in the other GLVs. In any case, it's fairly small and I don't think anyone will probably notice.

VOTE +1