Add OslcRequestParams and graph accumulation support to OslcClient

[Copilot]

Addresses #325: Enables configurable request parameters and graph accumulation in OslcClient, properly resolving #19 and #204 (header overwriting issues).

Changes

• OslcRequestParams class — Configures Accept, Content-Type, OSLC-Core-Version, and custom headers. Supports merge semantics for per-request overrides.

  • Pre-built configs: Default, RdfXmlOnly, TurtleOnly
  • Fluent Builder() API

• Graph accumulation — EnableGraphAccumulation() / DisableGraphAccumulation() for discovery phase workflows where responses should merge into a single graph

• Per-request parameter overrides — New overloads for GetResourceAsync and CreateResourceAsync accepting OslcRequestParams

• DefaultRequestParams property — Set globally in constructor or per-request

Usage

// Constructor-level defaults
var client = new OslcClient(logger, OslcRequestParams.RdfXmlOnly);

// Per-request override
var customParams = OslcRequestParams.Builder()
    .WithAccept("text/turtle")
    .WithHeader("X-Custom", "value")
    .Build();
await client.GetResourceAsync<ServiceProvider>(uri, null, customParams);

// Discovery with graph accumulation
var graph = client.EnableGraphAccumulation();
await client.GetResourceAsync<ServiceProviderCatalog>(catalogUri);
await client.GetResourceAsync<ServiceProvider>(spUri);
// graph now contains merged triples from both responses

Notes

• OslcRestClient remains deprecated (since 0.5.0)
• 21 new unit tests added
• All existing APIs unchanged

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Merge OslcClient and OslcRestClient</issue_title>
<issue_description>- [ ] Ensure #19 and #204 are solved properly. I am thinking of OslcRequestParams that we pre-set in the library, allow the user to set in the ctor, or to override on a per-request basis (mainly, to request/specify certain types, e.g. request only RDF/XML for root services or POST RDF/XML-ABBREV in some special cases)

• Allow access of both unmarshalled POCOs as well as access to the raw response graph.
• Allow the client to be set to accumulate the responses in a single graph - useful for the initial discovery phase.</issue_description>

<agent_instructions>OslcClient should remain. Increase test coverage during the join.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@berezovskyi OslcRestClient is largely deprecated since 0.5.0 - OslcClient is the primary client.

• Fixes Merge OslcClient and OslcRestClient #205

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[coderabbitai]

Important

Review skipped

Bot user detected.

To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.36%. Comparing base (0971a06) to head (45e27ee).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #468      +/-   ##
==========================================
+ Coverage   50.83%   51.36%   +0.53%     
==========================================
  Files         174      175       +1     
  Lines       10202    10306     +104     
  Branches     1010     1032      +22     
==========================================
+ Hits         5186     5294     +108     
+ Misses       4761     4752       -9     
- Partials      255      260       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.