How do I pass data to report_action()  in Odoo 11 Windows Enterprise?  (https://github.com/odoo/odoo/blob/11.0/odoo/addons/base/ir/ir_actions_report.py#L673 does not mention the data parameter)

I am using to report_action(); I added a button that prints my pdf template if I only pass the browse record parameter  but if I try to pass some data with the data parameter  I get a corrupted pdf that can not be opened with Adobe Reader; same template works fine without data (just the browse record).

This works:

@api.multi
def print_my_pdf_report(self, options):
    return self.env.ref('my_module_name.my_report_id').report_action(self)

But this does not work:

@api.multi
def print_my_pdf_report(self, options):
    # Some sample data 
    datas = {        
        'lines': [],          
        'report_name': 'My Report Name'
    }
    return self.env.ref('my_module_name.my_report_id').report_action(self, data=datas)

My sample template:

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data>
        <template id="my_sample_template">
            <t t-call="web.html_container">
                <t t-foreach="docs" t-as="o">
                    <t t-call="web.external_layout">
                        <div class="page">
                            <h2>Report title</h2>
                            <p>This object's name is
                                <span t-field="o.name"/>
                            </p>
                        </div>
                    </t>
                </t>
            </t>
        </template>
    </data>
</odoo>