How to use the extension point of other plugin? (Intellij Idea)

Question

For example, plugin Intellij Idea TestNG has extension point:

<extensionPoints >
    <extensionPoint qualifiedName="com.theoryinpractice.testng.listener" interface="org.testng.IDEATestNGListener"/>
</extensionPoints>

I want to use this extension point as follows:

<extensions defaultExtensionNs="TestNG-J">
    <com.theoryinpractice.testng.listener implementation="org.example.MyTestNGListener" />
</extensions>

public class MyTestNGListener implements org.testng.IDEATestNGListener {
    ...
}

But it did not work. What am I doing wrong?

(If there are errors, I'm sorry, did the translation from Google Translate)

Answer 1

defaultExtensionNs must have FQN prefix of EP, not plugin ID:

<extensions defaultExtensionNs="com.theoryinpractice.testng">
    <listener implementation="YourListenerFQN"/>
</extensions>

(http://devnet.jetbrains.com/message/5504720#5504720)