Error when YAML Config + List + Constructor-based converter

Describe the bug

I am getting a strange issue with lists in YAML configuration. The following works ok-ish:

@ConfigProperties
public interface BaseConfiguration {
    public Collection<MyListElement> mylist();

    public class MyListElement { 
        public String text;
        public MyListElement(final String text){ this.text = text.toUpperCase(); }
    }
}

Now I want to make sure I retain the order of the elements in mylist, hence I replace Collection by List. If I do so, Arc refuses the MyListElement class at compile time for not having a no-args constructor 🤔

Caused by: java.lang.IllegalArgumentException: Class 'org.acme.BaseConfiguration$MyListElement' which is used as return type of method 'mylist' in class 'org.acme.BaseConfiguration' must be have a no-args constructor
        at io.quarkus.arc.deployment.configproperties.YamlListObjectHandler.validateClass(YamlListObjectHandler.java:160)

Side-note the typo in the message requiring the class must be have a no-args constructor

If I add the constructor, snakeyaml crashes at run-time asking for a single-argument constructor for a synthetic class org.acme.BaseConfiguration$MyListElement_GeneratedListWrapper_mylist

Caused by: Can't construct a java object for tag:yaml.org,2002:org.acme.BaseConfiguration$MyListElement_GeneratedListWrapper_mylist; exception=No single argument constructor found for class org.acme.BaseConfiguration$MyListElement_GeneratedListWrapper_mylist : null
 in 'string', line 1, column 1:
    element,anotherElement
    ^

        at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:335)
...

Expected behavior

Expect List configuration entries to be working the same way as Collection entries.

Actual behavior

List configuration entries crash with using constructor-based converters.

To Reproduce

Reproducer here: https://github.com/someth2say/quarkus-issue-list-converter

Configuration

base: 
  mylist: 
    - element
    - anotherElement

Environment (please complete the following information):

Output of uname -a or ver

Linux localhost.localdomain 5.10.22-200.fc33.x86_64 #1 SMP Tue Mar 9 22:05:08 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

Output of java -version

openjdk version “11.0.10” 2021-01-19 OpenJDK Runtime Environment GraalVM CE 20.3.1 (build 11.0.10+8-jvmci-20.3-b09) OpenJDK 64-Bit Server VM GraalVM CE 20.3.1 (build 11.0.10+8-jvmci-20.3-b09, mixed mode, sharing)

GraalVM version (if different from Java)

Quarkus version or git rev

1.12.2.Final

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

Apache Maven 3.6.3 (cecedd343002696d0abb50b32b541b8a6ba2883f) Maven home: /home/jordisola/.m2/wrapper/dists/apache-maven-3.6.3-bin/1iopthnavndlasol9gbrbg6bf2/apache-maven-3.6.3 Java version: 11.0.10, vendor: GraalVM Community, runtime: /home/jordisola/.sdkman/candidates/java/20.3.1.r11-grl Default locale: en_GB, platform encoding: UTF-8 OS name: “linux”, version: “5.10.22-200.fc33.x86_64”, arch: “amd64”, family: “unix”

Additional context

(Add any other context about the problem here.) https://quarkusio.zulipchat.com/#narrow/stream/187030-users/topic/Errors.20with.20YAML.20config.20.2B.20List.20.20.2B.20Constructor-based.20conve.2E.2E.2E

[radcortez]

So we plan to replace the @ConfigPropeties interfaces implementation with the one from SR Config, so in the end they should work the same.

[someth2say]

Sure! The ConfigMapping approach worked for me.