Apache Velocity : Verify if all substitutions are made

--000000000000f0250405fdff9abf
Content-Type: text/plain; charset="UTF-8"

Can someone let me know how I can verify a velocity context against a
template? Basically, I want to throw some error if all variables are not
substituted in the velocity template.

For example, let's say I have a velocity template, card.vm

  card {
    type: CREDIT
    company: VISA
    name: "${firstName} ${lastName}"
  }

The substitution is done like below

VelocityEngine velocityEngine = new VelocityEngine();
velocityEngine.init();

Template t = velocityEngine.getTemplate("card.vm");

VelocityContext context = new VelocityContext();
context.put("firstName", "tuk");
StringWriter writer = new StringWriter();
t.merge( context, writer );

In this case, I want to throw some error specifying that lastName is not
replaced in template.

Does velocity provide anything for this?

--000000000000f0250405fdff9abf--