jdb: okhttp3/HttpUrl NoClassDefFoundError

Question

I have this code

// App.java
import okhttp3.HttpUrl;

public class App
{
  public static void main(String[] args) {
    HttpUrl url = HttpUrl.parse("https://example.com"); 
    // ...
  }
}

When I run $ gradle clean

$ gradle build

$ gradle run

It runs.

I wanted to debug the code as follows:

$ jdb -classpath build/classes/java/main/ -sourcepath src/main/java/ App
> stop in App.main
> run
> step

and it ends with error message:

> Exception in thread "main" java.lang.NoClassDefFoundError: okhttp3/HttpUrl
    at App.main(App.java:23)
Caused by: java.lang.ClassNotFoundException: okhttp3.HttpUrl
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
    ... 1 more

The application exited

Here is in my build.gradle

plugins {
    id 'java'
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'com.squareup.okhttp3:okhttp:4.9.0'
}

task runApp(type: JavaExec) {
    main = 'App'
    classpath = sourceSets.main.runtimeClasspath
}

How can I fix it?