[Quarkus drools] DroolsAssetsProcessor#generateSources threw an exception: java.lang.UnsupportedOperationException when no drl resources are presents

[dcdh]

I do not have any drl file present in the classpath because I manually load them following this way

Current behavior

When I start my test, the application fails to start with this stacktrace

java.lang.RuntimeException: java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step org.drools.quarkus.deployment.DroolsAssetsProcessor#generateSources threw an exception: java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractCollection.add(AbstractCollection.java:253)
	at org.drools.quarkus.deployment.DroolsAssetsProcessor.generateSources(DroolsAssetsProcessor.java:116)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:733)
	at io.quarkus.deployment.ExtensionLoader$3.execute(ExtensionLoader.java:856)
	at io.quarkus.builder.BuildContext.run(BuildContext.java:255)
	at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
	at org.jboss.threads.EnhancedQueueExecutor$Task.doRunWith(EnhancedQueueExecutor.java:2675)
	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2654)
	at org.jboss.threads.EnhancedQueueExecutor.runThreadBody(EnhancedQueueExecutor.java:1627)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1594)
	at java.base/java.lang.Thread.run(Thread.java:1583)
	at org.jboss.threads.JBossThread.run(JBossThread.java:499)


	at io.quarkus.test.junit.QuarkusTestExtension.throwBootFailureException(QuarkusTestExtension.java:611)
	at io.quarkus.test.junit.QuarkusTestExtension.interceptTestClassConstructor(QuarkusTestExtension.java:706)
	at java.base/java.util.Optional.orElseGet(Optional.java:364)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596)
Caused by: java.lang.RuntimeException: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step org.drools.quarkus.deployment.DroolsAssetsProcessor#generateSources threw an exception: java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractCollection.add(AbstractCollection.java:253)
	at org.drools.quarkus.deployment.DroolsAssetsProcessor.generateSources(DroolsAssetsProcessor.java:116)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:733)
	at io.quarkus.deployment.ExtensionLoader$3.execute(ExtensionLoader.java:856)
	at io.quarkus.builder.BuildContext.run(BuildContext.java:255)
	at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
	at org.jboss.threads.EnhancedQueueExecutor$Task.doRunWith(EnhancedQueueExecutor.java:2675)
	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2654)
	at org.jboss.threads.EnhancedQueueExecutor.runThreadBody(EnhancedQueueExecutor.java:1627)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1594)
	at java.base/java.lang.Thread.run(Thread.java:1583)
	at org.jboss.threads.JBossThread.run(JBossThread.java:499)

	at io.quarkus.runner.bootstrap.AugmentActionImpl.runAugment(AugmentActionImpl.java:372)
	at io.quarkus.runner.bootstrap.AugmentActionImpl.createInitialRuntimeApplication(AugmentActionImpl.java:289)
	at io.quarkus.runner.bootstrap.AugmentActionImpl.createInitialRuntimeApplication(AugmentActionImpl.java:61)
	at io.quarkus.test.junit.QuarkusTestExtension.doJavaStart(QuarkusTestExtension.java:195)
	at io.quarkus.test.junit.QuarkusTestExtension.ensureStarted(QuarkusTestExtension.java:578)
	at io.quarkus.test.junit.QuarkusTestExtension.beforeAll(QuarkusTestExtension.java:628)
	... 1 more
Caused by: io.quarkus.builder.BuildException: Build failure: Build failed due to errors
	[error]: Build step org.drools.quarkus.deployment.DroolsAssetsProcessor#generateSources threw an exception: java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractCollection.add(AbstractCollection.java:253)
	at org.drools.quarkus.deployment.DroolsAssetsProcessor.generateSources(DroolsAssetsProcessor.java:116)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:733)
	at io.quarkus.deployment.ExtensionLoader$3.execute(ExtensionLoader.java:856)
	at io.quarkus.builder.BuildContext.run(BuildContext.java:255)
	at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
	at org.jboss.threads.EnhancedQueueExecutor$Task.doRunWith(EnhancedQueueExecutor.java:2675)
	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2654)
	at org.jboss.threads.EnhancedQueueExecutor.runThreadBody(EnhancedQueueExecutor.java:1627)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1594)
	at java.base/java.lang.Thread.run(Thread.java:1583)
	at org.jboss.threads.JBossThread.run(JBossThread.java:499)

	at io.quarkus.builder.Execution.run(Execution.java:122)
	at io.quarkus.builder.BuildExecutionBuilder.execute(BuildExecutionBuilder.java:78)
	at io.quarkus.deployment.QuarkusAugmentor.run(QuarkusAugmentor.java:161)
	at io.quarkus.runner.bootstrap.AugmentActionImpl.runAugment(AugmentActionImpl.java:368)
	... 6 more
Caused by: java.lang.UnsupportedOperationException
	at java.base/java.util.AbstractCollection.add(AbstractCollection.java:253)
	at org.drools.quarkus.deployment.DroolsAssetsProcessor.generateSources(DroolsAssetsProcessor.java:116)
	at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:733)
	at io.quarkus.deployment.ExtensionLoader$3.execute(ExtensionLoader.java:856)
	at io.quarkus.builder.BuildContext.run(BuildContext.java:255)
	at org.jboss.threads.ContextHandler$1.runWith(ContextHandler.java:18)
	at org.jboss.threads.EnhancedQueueExecutor$Task.doRunWith(EnhancedQueueExecutor.java:2675)
	at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2654)
	at org.jboss.threads.EnhancedQueueExecutor.runThreadBody(EnhancedQueueExecutor.java:1627)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1594)
	at java.base/java.lang.Thread.run(Thread.java:1583)
	at org.jboss.threads.JBossThread.run(JBossThread.java:499)

Expected behavior

My application should start.

Additional informations

This issue is due to the fact that we want to add an element to an unmodifiable collection.

Following this code

        Collection<GeneratedFile> generatedFiles = ruleCodegen.generate();
        generatedFiles.addAll(getRuleUnitDefProducerSource(combinedIndexBuildItem.getIndex()));

        // The HotReloadSupportClass has to be generated only during the first model generation
        // During actual hot reloads it will be regenerated by the compilation providers in order to retrigger this build step
        if (!liveReload.isLiveReload()) {
            generatedFiles.add(new GeneratedFile(GeneratedFileType.SOURCE, HOT_RELOAD_SUPPORT_PATH + ".java", getHotReloadSupportSource()));
        }

The ruleCodegen will generate a Collection of GeneratedFile.
Next - because we are not in a live reload context - another GeneratedFile will be added to this collection. Moreover, I am quite surprise about it, because the item is in relation with the hot reload and so, maybe it should be added when it is in live reload context ?

But, now regarding the way ruleCodegen generate work

    public final Collection<GeneratedFile> generate() {
        if (isEmpty()) {
            return Collections.emptySet();
        }
        return internalGenerate();
    }

and so the isEmpty()

    public boolean isEmpty() {
        return resources.isEmpty();
    }

In my case, I do not have any drl resources because I load them at runtime using multiline String (in a next version I will store them in another deployment tool). And so the generate method will return an emptySet Collections - which is an unmodifiable Set - and so adding a new item will fail.

Could you please:

1. return a modifiable Set
2. also validate the adding the hot reload support GeneratedFile when not in live reload.

Thanks.

Regards,

Damien