Error when loading a class (cheerpjRunLibrary)

try {
    console.log("initializing")
    await cheerpjInit()
    console.log("initializing done")
} catch (e) {
    console.log("initializing failed")
    throw e
}

try {
    console.log("loading jar file")
    lib = await cheerpjRunLibrary("/app/cheerpjtest/target/cheerpjtest-1.0-SNAPSHOT.jar")
    console.log("loading jar file done")
} catch (e) {
    console.log("loading jar file failed")
    throw e
}

try {
    console.log("loading class")
    MyClass = await lib.com.example.MyClass
    console.log("loading class done")
} catch (e) {
    console.log("loading class failed")
    throw e
}

.
├── cheerpjtest
│   ├── pom.xml
│   ├── src
│   │   └── main
│   │       └── java
│   │           └── com
│   │               └── example
│   │                   └── cheerpjtest
│   │                       └── MyClass.java
│   └── target
│       └── cheerpjtest-1.0-SNAPSHOT.jar
└── index.html

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.example</groupId>
  <artifactId>cheerpjtest</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
  </properties>
</project>

package com.example;

public class MyClass {
    public static int timesTwo(int n) {
        return n * 2;
    }
}