Qute: generation of qute-i18n-examples doesn't handle localized enums

[phetta-remion]

Describe the bug

When I have message accepting a single enum parameter as part of my message bundle, a maven quarkus application fails while doing mvn install with the following message

Cannot invoke "org.jboss.jandex.MethodInfo.name()" because the return value of "io.quarkus.qute.deployment.MessageBundleMethodBuildItem.getMethod()" is null.

This is probably because MessageBundleProcessor#generateExamplePropertiesFiles() is trying to generate example properties keys by using the build item method names, and build items generated by generateEnumConstantMessageMethod() creates build items without methods.

Expected behavior

Message bundle processor correctly generates example properties file even when auto-generated message keys for enums are present.

Actual behavior

Message bundle processor crashes when encountering auto-generated enum messages.

How to Reproduce?

Create a qute project with the following files:
FooMessages.java

@MessageBundle("foo")
public interface FooMessages {
    @Message
    String enum_message(MyEnum period);
}

MyEnum.java

public enum MyEnum {
    A,
}

/resources/messages/foo_en_US.properties

enum_message_A=A

Run mvn install to build and package. Crashes with the above mentioned error message.

Output of uname -a or ver

No response

Output of java -version

OpenJDK Temurin 17.0.12

Quarkus version or git rev

3.16.1

Build tool (ie. output of mvnw --version or gradlew --version)

Maven 3.8.7

Additional information

No response

[quarkus-bot]

/cc @mkouba (qute)