Unable to access data which passed from main template to header

[vijaygohil1223]

i am passing data in header from main template like this
{{{pdfAddPageItem variable="Mystring"}}}

then how can I get this variable in the header template

https://playground.jsreport.net/w/anon/4gLEBGyi

when run in debug mode its shows...
Pdf utils adding item field, value: {"age":33,"name":"Jan"}

But unable to access this.

[jan_blaha]

See the updated demo.
https://playground.jsreport.net/w/anon/EVbYOnJA