아래와 같이 확인해보시면 될 거 같습니다.
// In the caver, almost everything starts with the caver. Let's create a caver instance
HttpService httpService = new HttpService(nodeApiUrl);
httpService.addHeader("Authorization", Credentials.basic(accessKeyId, secretAccessKey));
httpService.addHeader("x-chain-id", chainId);
Caver caver = new Caver(httpService);
HashMap<String, String> headers = ((HttpService)caver.currentProvider).getHeaders();
System.out.println(headers);