optaplanner-examples/src/main/java/org/optaplanner/examples/nqueens/app/NQueensApp.java
protected Solver<NQueens> createSolverByXml() {
        SolverFactory<NQueens> solverFactory = SolverFactory.createFromXmlResource(SOLVER_CONFIG);
        return solverFactory.buildSolver();
    }
protected Solver<NQueens> createSolverByXml() {
        SolverFactory<NQueens> solverFactory = SolverFactory.createFromXmlResource(SOLVER_CONFIG);
        return solverFactory.buildSolver();
    }
Normal way to create a {@link Solver}.
@return never null