When creating a QtCreator plugin project one file generated is <pluginname>.json.in which has the content

{{{}}
{{ "Name" : "MyPlugin",}}
{{ "Version" : "0.0.1",}}
{{ "CompatVersion" : "0.0.1",}}
{{ "Vendor" : "MyCompany",}}
{{ "Copyright" : "(C) MyCompany",}}
{{ "License" : "Put your license information here",}}
{{ "Description" : "Put a short description of your plugin here",}}
{{ "Url" : "http://www.mycompany.com",}}
{{ $$dependencyList}}
}

But after compiling a warning appears refering to the generated .json file:

Warning: Plugin Metadata file "MyPlugin.json" does not contain a valid JSON object. Declaration will be ignored

The only way to get ride off this warning is adding a \" (backslash and quote) after each quote (")  to compile correctly the plugin and even with that the plugin is not show in the Tools Menu of the QtCreator built from source.