I will try and make this factual and short along with info I think will be asked.
I am 6 months in to a new job which I love.
It's a niche role in a council.
I am 42 yo and in the past I have done many roles including managing 30 plus people but I have come in to this role at lower level despite having over 10 years experience in this field.
My team leader is 24. Nice enough and doing the teamleader role as a temp role as part of his management course. It was a 12 month secondment which is now up however lockdown has stopped normal recruitment processes.
We get on I like him and we talk a fair bit about the job and what it entails. I naively thought we were just shooting the shit.
I have found out today that some ideas I discussed with him including major project work, he has passed off to upper management as his own.
Some of the things I said were quiet specific and definitely came from me. Management have loved his ideas and in particular an analogy I used to show that something would not work. They praised him for HIS critical thinking 
How do I deal with this?
I dont think calling him out will solve this or paint me in a good light but I do want management to know his ideas are mine. So how would you tackle this?
Any advice is appreciated.