generate wrong binary file using JSON-based wizard

Hi,
My custom wizard project contains a PNG file. I write "generators" in wizard.json as below:
"generators":
[
{
"typeId": "File",
"data":
[

{ "source": "icon.png", "target": "icon.png" }

]
}
]

But when I generate a project using this wizard, the icon.png has wrong size and can't open by image viewer.
There's no "binary" property in JSON-based wizard like in XML-based, perhaps it's treated as a text file?