从SolutionFolder中取出Project
Solution3 solution = this.CurrentSolution as Solution3;
Project project = solution.AddSolutionFolder(perfix);
SolutionFolder sf = project.Object as SolutionFolder;
sf.AddFromFile("d:\\a.csproj");
这时候我想从sf中取出这个a.csproj,但是SolutionFolder没有这个接口,请问怎么实现?