Java::JavaLang::ClassCastException: class java.lang.Integer cannot be cast to class java.lang.String #8847
Description
Context:
Hello from AWS SDK for Ruby! We're updating our CI to include JRuby 10 as part of the GitHub workflow and have been encountering an error when attempting to build our service gems via rake command. Any guidance or hints to debug are appreciated! Thanks in advance.
Environment information
JRuby version:
jruby 10.0.0.1 (3.4.2) 2025-05-07 79cf1e4aec OpenJDK 64-Bit Server VM 21.0.7+6-LTS on 21.0.7+6-LTS +indy +jit [x86_64-linux]
Additional resources:
Expected Behavior
When running our rake command, bundle exec rake build - it should successfully build w/o failures. We do not have any issues building in Jruby 9.4
Actual Behavior
Logs are quite verbose, so I have attached a link to our CI logs: https://github.com/aws/aws-sdk-ruby/actions/runs/15278381788/job/42970671365
Caused by:
Java::JavaLang::ClassCastException: class java.lang.Integer cannot be cast to class java.lang.String (java.lang.Integer and java.lang.String are in module java.base of loader 'bootstrap') (Java::JavaLang::ClassCastException)
org.jruby.dist/org.jruby.ir.targets.indy.BuildDynamicStringSite.<init>(BuildDynamicStringSite.java:89)
org.jruby.dist/org.jruby.ir.targets.indy.BuildDynamicStringSite.buildDString(BuildDynamicStringSite.java:42)
java.base/java.lang.invoke.BootstrapMethodInvoker.invoke(BootstrapMethodInvoker.java:147)
java.base/java.lang.invoke.CallSite.makeSite(CallSite.java:316)
java.base/java.lang.invoke.MethodHandleNatives.linkCallSiteImpl(MethodHandleNatives.java:274)
java.base/java.lang.invoke.MethodHandleNatives.linkCallSite(MethodHandleNatives.java:264)
home.runner.$_dot_rubies.jruby_minus_10_dot_0_dot_0_dot_1.lib.ruby.gems.shared.gems.mustache_minus_1_dot_1_dot_1.lib.mustache.template.️❤ def render #0(/home/runner/.rubies/jruby-10.0.0.1/lib/ruby/gems/shared/gems/mustache-1.1.1/lib/mustache/template.rb:979)
Reproduction Steps
- Clone SDK repo
- Bundle install
- run
bundle exec rake build