[diazweb]

Summary

Fixes #181 without raising jsonpath's Ruby requirement or forcing older Ruby users onto multi_json 1.21 (which requires Ruby >= 3.2).

• Use MultiJSON.parse when the modern constant exists. This avoids both the deprecated MultiJson constant and the deprecated decode/load methods introduced in multi_json 1.21. Merely replacing decode with load would still warn on current releases.
• Otherwise use the supported legacy MultiJson.load API. Declare its minimum multi_json version (1.3) in the gemspec.
• Preserve non-string inputs and forwarding of max_nesting.
• Add a fresh-process regression with warnings enabled, so multi_json's warn-once behavior cannot conceal a regression depending on test order. Update the existing nesting-error assertion to use the canonical constant where available.

Validation

Ruby 4.0.7, upstream's declared minitest 2.2.2:

ruby -W:deprecated -Ilib -e 'gem "minitest", "2.2.2"; gem "multi_json", "1.21.1"; load "test/test_jsonpath.rb"'
ruby -W:deprecated -Ilib -e 'gem "minitest", "2.2.2"; gem "multi_json", "1.15.0"; load "test/test_jsonpath.rb"'

Each: 119 tests, 187 assertions, 0 failures, 0 errors, 2 existing skips. These are the core test/test_jsonpath.rb tests, not a claim that the entire Rake/CLI suite or older Ruby matrix was run. Before the implementation change, the new warning regression failed with both the deprecated constant and decode warnings.

Also verified the downstream k8s-ruby 0.18.0 K8s::Transport.token_from_auth_provider command-output/token-key path with a local /usr/bin/printf fixture, no cluster/network access: same extracted token before/after; both warnings before, no warnings after. Explicit-token client initialization does not invoke JsonPath.

Scope

Draft for maintainer review. No consumer fork dependency, monkeypatch, warning suppression, Ruby requirement change, or unrelated dependency upgrade. A released jsonpath fix is needed before downstream applications can consume this through a normal gem update.