What is the syntax used to wrap multiple DLLs with "bin" in project.json

I have an ASP.Net 5 (vNext) solution that needs to reference many locally created DLLs. I have attempted different versions of the syntax in project.json to indicate the dlls. My attempts have either ended in syntax errors or (the most promising one) says that "cannot cast a Newtonsoft.Json.Linq.JArray to a Newtonsoft.Json.Linq.JToken".

The syntax that generated the error above was

"frameworks":
{
    "aspnet50":
    {
        "bin":
        {
            "assembly":
            [
                "C:\\foo.dll",
                "C:\\bar.dll"
            ],
            "pdb":
            [
                "C:\\foo.pdb",
                "C:\\bar.pdb"
            ]
        }
    }
},

There is no way to wrap multiple DLLs with a single project.json. You have to create one project.json for each DLL.