If your JSON definition looks like this:
{
"label": "Name",
"value": "Example"
}
it indicates a single object / row. In that case, you can change it to
[
{
"label": "First label",
"value": "Example value"
},
{
"label": "Second label",
"value": "Example value 2"
}
]
which will let the mapping return a list of these objects.