Java: Connect Gradle with Velocity

I'm trying to connect Velocity with Gradle builder. So I created a Gradle project in IntelliJ, put the Gradle-Velocity-Plugin into the project directory, imported the Velocity jar and created the following files:

build.gradle:

group 'xxxxx'
version '1.0-SNAPSHOT'

apply plugin: 'java'


sourceCompatibility = 1.5

repositories {
    mavenCentral()
    jcenter()
}

buildscript {
    repositories {
        mavenCentral()
        jcenter()
    }

    dependencies {
        classpath 'org.anarres.gradle:gradle-velocity-plugin:[1.0.0,)'
    }
}

apply plugin: 'velocity'
 
jar {
    manifest {
        attributes 'Main-Class': 'test.HelloWorld'
    }
}

HelloWorld.java:

package test;

import java.io.StringWriter;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.runtime.RuntimeConstants;
import org.apache.velocity.runtime.resource.loader.ClasspathResourceLoader;

public class HelloWorld
{
    public static void main(String[] args)
    {
        try {
            VelocityEngine ve = new VelocityEngine();
            ve.setProperty(RuntimeConstants.RESOURCE_LOADER, "classpath");
            ve.setProperty("classpath.resource.loader.class", ClasspathResourceLoader.class.getName());
            ve.init();
            VelocityContext context = new VelocityContext();
            context.put("name", "World");
            Template t = ve.getTemplate( "helloworld.vm" );
            StringWriter writer = new StringWriter();
            t.merge( context, writer );
            System.out.println( writer.toString() );
        }
        catch (Exception e) {
            System.out.println("failed");
        }
    }
}

Now, when I execute gradle tasks, everything is fine, but when I execute gradle assemble, I get errors, that the velocity packages do not exist.

Does anyone of you got an idea how to fix this?
Thank you.