Does anyone know or has experience with a pure Java library to select portfolios or do some similar kinds of quadratic programming with constraints?

There seems to be a lot of tools, as already discussed elsewhere - but what I would like to use is a pure Java implementation. Since I want to call the library from within another open-source software with a BSD-ish license I would prefer LGPL over GPL.

Any help is appreciated. If you don't know such libraries, which is the most simple algorithm you would suggest to implement? It has to cope with an inequality constraint (all x_i >= 0) and an equality constraint (sum of all x_i = 1).