Send messages from Java with the SendiMessage API

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class SendMessage {
    public static void main(String[] args) throws Exception {
        String body = """
            {
              "number": "+15555550123",
              "content": "Hello from SendiMessage"
            }""";

        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.sendimessage.com/v1/send-message"))
            .header("X-API-Key", System.getenv("SENDIMESSAGE_KEY"))
            .header("X-API-Secret", System.getenv("SENDIMESSAGE_SECRET"))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(body))
            .build();

        HttpResponse<String> response = HttpClient.newHttpClient()
            .send(request, HttpResponse.BodyHandlers.ofString());

        if (response.statusCode() >= 300) {
            throw new RuntimeException("SendiMessage error " + response.statusCode() + ": " + response.body());
        }
        System.out.println(response.body()); // {"message_handle":"4e828182-…","status":"QUEUED",…}
    }
}