Java Apache Commons Math, linear least squares (fit) with constraints

I am trying to use the Apache Commons Math library in Java (latest version) to solve the linear least squares problem where there is a constraint on the solution.

In particular, I want the solution to contain only positive values. In other words, I want to find the best fit for my base functions so that the weight of the solution is greater than 0.

If someone has already tracked down this issue and solved it, I would appreciate a solution!