Reports

Like Ondro suggested, adding the <context-param> to web.xml was necessary:

<context-param>
    <param-name>jakarta.faces.FACELETS_LIBRARIES</param-name>
    <param-value>/WEB-INF/example.taglib.xml</param-value>
</context-param>

But in addition also modifying @FacesConfig of DataList.java:

@FacesComponent(value = "com.example.component.DataList")
public class DataList extends UIData {

Otherwise DataList still couldn't be found.

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