"already initialized constant" warning is emitted when accessing Document.getStructuredDoctitle

[zeldigas]

I'm using v3.0.0 of asciidoctorj and observing that ruby emits warning:

(unknown):0: warning: already initialized constant org.jruby.gen::InterfaceImpl1274018768

After some debugging, I spotted the place - this happens when I call getStructuredDocttitle in my code:

val document = ADOC.loadFile(file.toFile(), headerParsingOptions())
val title = doc.structuredDoctitle?.combined ?: null //here is warning emitted

Stack trace:

setConstantCommon:4981, RubyModule (org.jruby)
setConstant:4949, RubyModule (org.jruby)
setProxyClass:266, Java (org.jruby.javasupport)
addToJavaPackageModule:868, Java (org.jruby.javasupport)
getProxyClassFromCache:378, JavaSupport (org.jruby.javasupport)
getProxyClass:441, Java (org.jruby.javasupport)
getProxyClass:434, Java (org.jruby.javasupport)
getInstance:299, Java (org.jruby.javasupport)
getInstance:281, Java (org.jruby.javasupport)
newInterfaceProxy:311, JavaInterfaceTemplate (org.jruby.java.proxies)
access$100:59, JavaInterfaceTemplate (org.jruby.java.proxies)
call:259, JavaInterfaceTemplate$InterfaceProxyFactory (org.jruby.java.proxies)
call:212, DynamicMethod (org.jruby.internal.runtime.methods)
finvoke:598, RubyClass (org.jruby)
invoke:708, Helpers (org.jruby.runtime)
convertProcToInterface:267, JavaUtil (org.jruby.javasupport)
defaultToJava:818, RubyBasicObject (org.jruby)
toJava:797, RubyBasicObject (org.jruby)
rubyToJava:263, JavaEmbedUtils (org.jruby.javasupport)
toJava:160, RubyObjectWrapper (org.asciidoctor.jruby.internal)
getStructuredDoctitle:48, DocumentImpl (org.asciidoctor.jruby.ast.impl)
documentTitle:35, AsciidocFileConverter (com.github.zeldigas.text2confl.convert.asciidoc)
computeTitle:31, AsciidocFileConverter (com.github.zeldigas.text2confl.convert.asciidoc)
toHeader:23, AsciidocFileConverter (com.github.zeldigas.text2confl.convert.asciidoc)
readHeader:16, AsciidocFileConverter (com.github.zeldigas.text2confl.convert.asciidoc)
Read header from first header$convert:95, AsciidocFileConverterTest (com.github.zeldigas.text2confl.convert.asciidoc)

Observations:

1. All calls are single threaded, so it does not look like directly related to Concurrent use of AsciidoctorJ Asciidoctor interface results in ConcurrentModificationException #1158.
2. It started happening after upgrade to version 3. Version 2.5.13 did not have this issue
   B
3. This happens on subsequent calls to getStructuredDocttitle. Just creating fresh asciidoctor instance, parsing doc and calling this method does not reveal the problem

[zeldigas]

Reproduction of this behavior in text2confl project tests:

Introduced change: zeldigas/text2confl@3173d09
Build that reveals this warning in tests: https://github.com/zeldigas/text2confl/actions/runs/15776392138/job/44471732810#step:5:351

Previous build does not have such warning: https://github.com/zeldigas/text2confl/actions/runs/15758128631/job/44418093051

Place where this is invoked: https://github.com/zeldigas/text2confl/blob/master/convert/src/main/kotlin/com/github/zeldigas/text2confl/convert/asciidoc/AsciidocFileConverter.kt#L35

[robertpanzer]

Please provide a reproducer for this.
I was NOT able to reproduce with this small test program:

    public static void main(String[] args) {
        try (var asciidoctor = Asciidoctor.Factory.create()) {
            Document doc = asciidoctor.load("= Test\n\nTest\n", Options.builder()
                    .option("parse_header_only", true)
                    .build());
            Title structuredDoctitle = doc.getStructuredDoctitle();
            String result = structuredDoctitle.getCombined();
            System.out.println(result);
            Title structuredDoctitle2 = doc.getStructuredDoctitle();
            String result2 = structuredDoctitle2.getCombined();
            System.out.println(result2);

            Document doc2 = asciidoctor.load("= Test\n\nTest\n", Options.builder()
                    .option("parse_header_only", true)
                    .build());
            Title structuredDoctitle3 = doc2.getStructuredDoctitle();
            String result3 = structuredDoctitle3.getCombined();
            System.out.println(result3);
        }
    }

The output from this program looks like this for me:

> java Test
2025-06-28T14:41:19.612+02:00 [main] WARN FilenoUtil : Native subprocess control requires open access to the JDK IO subsystem
Pass '--add-opens java.base/sun.nio.ch=ALL-UNNAMED --add-opens java.base/java.io=ALL-UNNAMED' to enable.
Test
Test
Test

Tested with asciidoctorj 3.0.0 and jruby-complete 9.3.8.0.
Could not reproduce with jruby 9.4.13.0 either.

[zeldigas]

OK. I'll work on it in a week