[Bug]: JRuby build no longer available, causing gem installation to fail

[Euklios]

Problem Description

The instana gem previously provided builds compatible with JRuby. However, after version 1.11.8, no JRuby-compatible builds appear to be published.

This causes gem installation to fail when using a newer version, due to the oj native extension dependency. The oj gem is known to be incompatible with JRuby, but it's already conditionally excluded in the gemspec for JRuby platforms.

Since there is no published JRuby-specific build, Bundler attempts to install the default (MRI) version, which fails due to the native extension.

Current workaround:

We're currently vendoring the gem in our repository as a workaround, but it would be preferable to have regular JRuby-compatible builds published again.

Minimal, Complete, Verifiable, Example

Steps to reproduce:

1. Create a JRuby project.
2. Add gem 'instana' to the Gemfile.
3. Run bundle install.
4. Observe failure due to oj native extension.

Gemfile.lock

PATH
  remote: .
  specs:
    sample_proj (0.1.0)

GEM
  remote: https://rubygems.org/
  specs:
    date (3.4.1-java)
    erb (5.0.2-java)
    io-console (0.8.1-java)
    irb (1.15.2)
      pp (>= 0.6.0)
      rdoc (>= 4.0.0)
      reline (>= 0.4.2)
    jar-dependencies (0.5.5)
    pp (0.6.2)
      prettyprint
    prettyprint (0.2.0)
    psych (5.2.6-java)
      date
      jar-dependencies (>= 0.1.7)
    rake (13.3.0)
    rdoc (6.14.2)
      erb
      psych (>= 4.0.0)
    reline (0.6.2)
      io-console (~> 0.5)

PLATFORMS
  universal-java-21

DEPENDENCIES
  irb
  rake (~> 13.0)
  sample_proj!

BUNDLED WITH
   2.7.1

Ruby Version

JRuby 10.0.1.0 (Ruby 3.4.2)
Java 21.0.7

`jruby 10.0.1.0 (3.4.2) 2025-07-17 0f10d1dfdf OpenJDK 64-Bit Server VM 21.0.7+6-LTS on 21.0.7+6-LTS +indy +jit [x86_64-linux]`