For generate java classes, you can use Json file with attributes in tree nodes.
See here.
const { JsonToJava } = require('json-2-java');
const fs = require('fs');
const readJsonFileContent = path => {
return JSON.parse(fs.readFileSync(path).toString());
};
const java_class_result = JsonToJava.processJavaClass(
readJsonFileContent('my_json.json')
);
fs.writeFileSync('MyClass.java', java_class_result);