ExampleAssetFilter.java

package com.example.preloader.gen;

import com.badlogic.gdx.backends.gwt.preloader.DefaultAssetFilter;
 
public class ExampleAssetFilter extends DefaultAssetFilter {

  @Override
	public String getBundleName (String file) {
		return super.getBundleName(file);
	}
 
}

GwtDefinition.gwt.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<module>
    <entry-point class="com.example.preloader.client.GwtLauncher"/>
    <set-configuration-property name="gdx.assetpath" value="../example-android/assets"/>
    <set-configuration-property name="gdx.assetfilterclass" value="com.example.preloader.gen.ExampleAssetFilter"/>
    <inherits name="ExampleGame"/>
    <inherits name="com.badlogic.gdx.backends.gdx_backends_gwt"/>
</module>