Install eclipse-wtp-xmltools by entering the following commands in the terminal:
sudo apt update sudo apt install eclipse-wtp-xmltools
Eclipse XML tools and editors
The Eclipse Web Tools Platform (WTP) project extends the Eclipse platform with tools for developing Web and Java EE applications. It includes source and graphical editors for a variety of languages, wizards and built-in applications to simplify development, and tools and APIs to support deploying, running, and testing apps. . This package contains source and graphical editors for XML, DTD and XML schema (XSD) files.