"Property processName is not allowed." in launch.json

I am quickly copying this issue from microsoft/vscode#48844 so it is formatted according to VS code's own issue rules and not vscode-cpptools. That said, the information provided here should be enough to solve the issue.

VSCode Version: 1.22.2
OS Version: Windows 10

The config.json parser does not recognize the new processName parameter, only the processId one. Therefore, if you put processName but not processId, you'll get 2 warnings in the issues list:

Missing property "processId"
Property processName is not allowed.

Steps to Reproduce:

Create a `launch.json` configuration with this:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "(Windows) Attach",
            "type": "cppvsdbg",
            "request": "attach",
            "processName": "my_program.exe"
        }
    ]
}

Open the Issues panel or go to next error (F8) to see the 2 errors mentioned at the beginning.

In addition, processName is not yet mentioned in launch.md.