Code injection in xml not showing

Hi, I'm working on some custom injection.
What i would like to inject is some groovy in the following structure (after groovy keyword) for example:

<set field="placeholderValues.fromDate" value="${groovy:nowTimestamp.toString()}"/>

From what i read from the doc, for simple injection no code is needed, only config, so i have this :
in plugin.xml file:

<depends config-file="xml-injections.xml">org.intellij.intelliLang</depends>

in a xml-injection.xml file :

<idea-plugin>
    <extensions defaultExtensionNs="org.intellij.intelliLang">
        <injectionConfig config="OfbizGroovyInjections.xml"/>
    </extensions>
</idea-plugin>

and in OfbizGroovyInjections.xml file :

<?xml version="1.0" encoding="UTF-8"?>
<component name="LanguageInjectionConfiguration">
    <injection language="Groovy" injector-id="xml">
        <display-name>OFBiz groovy injection</display-name>
        <single-file value="false"/>
        <prefix>${groovy:</prefix>
        <suffix>}</suffix>
        <place><![CDATA[
            xmlAttribute().withValue(string().contains("{groovy:"))
            ]]></place>
    </injection>
</component>

The injection shows up in the dev instance with the right pattern, but for some reason it doesn't seem to actualy inject anything.
Am i missing something obvious here ?
Or do i need to implement a LangageInjector (though i seems a bit overkilled for simple injection)
I oppened a slack topic about this (got no answer yet though):
https://jetbrains-platform.slack.com/archives/C5U8BM1MK/p1675246191149869
Any help is welcome !