In VSCODE how to run a task automatically when a source file is edited?

In Visual Studio Code (VSCode), working with a mavenized Java web application, which I call sfeaapp project.

What can be done so that every time a source or resource of that sfeaapp project is changed, the mvn package task is automatically executed?

I have defined the following task in tasks.json, but I don't know how to make it fire automatically when I edit and save a project file, for example a .jsp:

    {
        "version": "2.0.0",
        "tasks": [
            {
                "label": "auto package",
                "type": "shell",
                "command": "mvn package -f C:\\VSCODE_PROJECTS\\sfeaapp\\pom.xml",
                "args": [],
                "group": "build",
                "presentation": {
                    "reveal": "always",
                    "panel": "shared"
                },
                "problemMatcher": []
            }
        ]
    }

The task auto package works fine if I launch it explicitly.

with the use of the extension multi-command you can re-define the keybinding for Ctrl+S to save the file and call the task after a small wait.

Add to your keybindings.json

{
    "key": "ctrl+s",
    "command": "extension.multiCommand.execute",
    "args": {
        "interval": 1000,
        "sequence": [
            "workbench.action.files.save",
            { "command": "workbench.action.tasks.runTask",
              "args": "auto package" }
        ]
    },
    "when": "resourceDirname == /users/mememe/project/src"
}

Adjust the directory to the workspace directory path.