Constraint solving with choco: Finding unique solutions for a variable

Question

I'm using Choco to solve a CSP. In the beginning, I create an array of variables v like this:

IntVar[] v = new IntVar[5];

After adding several constraints, I'll search for solutions and find multiple of them. However, I want only unique solutions for e.g. v[4]. So all solutions should have a different value in the v[4] variable.

How can I achieve this?