JSON File is imported for theme, fonts not updating

I am trying to use Roboto font in my pbix. I have created a json file. It says that import is successful. However, it just changes the colors. Font style remain as is. 
Below is the script I am using for json.
{
"name": "Theme",
"dataColors": ["#1a661f","#2b9630","#aac811","#F18643","#e52600","#73b0db","#335c73","#7E6996"],
"textClasses": {
"callout": {
"fontSize": 45,
"fontFace": "Roboto",
"color": "#252423"
},
"title": {
"fontSize": 12,
"fontFace": "Roboto",
"color": "#252423"
},
"header": {
"fontSize": 12,
"fontFace": "Roboto",
"color": "#252423"
},
"label": {
"fontSize": 10,
"fontFace": "Roboto",
"color": "#252423"
}
}
}

If it changes then it displays the "Times New roman" fonts but in visuals pane it will say "Roboto".