Run com.example.FeignBug.test
Observe logs for regular string value of header (correct):
14:32:07.995 [Test worker] DEBUG com.example.TestClient - [TestClient#get] ---> GET https://www.google.com/ HTTP/1.1
14:32:07.998 [Test worker] DEBUG com.example.TestClient - [TestClient#get] Custom: val
And for json value (truncated):
14:42:34.815 [Test worker] DEBUG com.example.TestClient - [TestClient#get] ---> GET https://www.google.com/ HTTP/1.1
14:42:34.815 [Test worker] DEBUG com.example.TestClient - [TestClient#get] Custom: {"string": "val", "string2"}