Demo of asciidoctor/asciidoctor-gradle-plugin#493

If you run ./gradlew asciidoctor it fails with:

Jan 24, 2020 12:07:15 PM uri:classloader:/gems/asciidoctor-2.0.10/lib/asciidoctor/converter/html5.rb convert_document
WARNING: /home/rwinch/code/rwinch/asciidoctor-gradle-resource-failure/src/docs/asciidoc/index.adoc: stylesheet does not exist or cannot be read: /home/rwinch/code/rwinch/asciidoctor-gradle-resource-failure/css/custom.css
Exception in thread "main" org.asciidoctor.gradle.remote.AsciidoctorRemoteExecutionException: ERROR: The following messages from AsciidoctorJ are treated as errors:
/home/rwinch/code/rwinch/asciidoctor-gradle-resource-failure/src/docs/asciidoc/index.adoc: stylesheet does not exist or cannot be read: /home/rwinch/code/rwinch/asciidoctor-gradle-resource-failure/css/custom.css
        at org.asciidoctor.gradle.remote.ExecutorBase.failOnWarnings(ExecutorBase.groovy:223)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
        at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)
        at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1041)
        at org.codehaus.groovy.runtime.InvokerHelper.invokePogoMethod(InvokerHelper.java:1011)
        at org.codehaus.groovy.runtime.InvokerHelper.invokeMethod(InvokerHelper.java:994)
        at org.codehaus.groovy.runtime.InvokerHelper.invokeMethodSafe(InvokerHelper.java:97)
        at org.asciidoctor.gradle.remote.AsciidoctorJavaExec$_run_closure3.doCall(AsciidoctorJavaExec.groovy:74)
        at org.asciidoctor.gradle.remote.AsciidoctorJavaExec$_run_closure3.call(AsciidoctorJavaExec.groovy)
        at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2330)
        at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2315)
        at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2356)
        at org.asciidoctor.gradle.remote.AsciidoctorJavaExec.run(AsciidoctorJavaExec.groovy:67)
        at org.asciidoctor.gradle.remote.AsciidoctorJavaExec.main(AsciidoctorJavaExec.groovy:49)

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':asciidoctor'.
> Remote Asciidoctor process failed to complete successfully

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 3s
1 actionable task: 1 executed

If fatalWarnings ".*" is commented out, the build will produce a warning, but custom.css will there. The reason appears to be because copying the resources happens afterwards.

I’d like to be able to fail on warnings so that we can catch problems with the build.