How to set up UTF-8 in a REST service on Amazon API Gateway?

Question

RESTful API

Hello!
How to set up correct transmission of UTF-8 strings to REST service?
Environment: table in DynamoDB, accessed via REST in Amazon API Gateway.
Test working: https://n3i92lcyj8.execute-api.eu-west-3.amazonaws...
Test fails (in browser): https://n3i92lcyj8.execute-api.eu-west-3.amazonaws.. In Java (through the
Jersey Client) it also returns null for username Petr, I pass it on for everyone, with encode / without - for some reason the data does not come.
Tests (in Amazon API Gateway interface) pass fine, data is requested:

Thank you.