add method to explicitly set the Last-Event-ID header

Author: ryber

unirest-bdd-tests/src/test/java/BehaviorTests/MockServer.java

@@ -105,6 +105,7 @@ public static void reset() {
         WebSocketHandler.reset();
         retryTimes = 0;
         errorCode = 400;
+        lastRequest = null;
     }
 
     static {

unirest-bdd-tests/src/test/java/BehaviorTests/SSEStreamTest.java

@@ -99,4 +99,15 @@ void sendHeaders() {
                 .assertHeader("fruit", "apple")
                 .assertCookie("snack", "snickerdoodle");
     }
+
+    @Test
+    void canSendLastEventIdHeader() {
+        Unirest.sse(MockServer.SSE)
+                .lastEventId("42")
+                .connect()
+                .collect(Collectors.toList());
+
+        MockServer.lastRequest()
+                .assertHeader("Last-Event-ID", "42");
+    }
 }

unirest/src/main/java/kong/unirest/core/SseRequest.java

@@ -152,6 +152,13 @@ public interface SseRequest {
      */
     Headers getHeaders();
 
+    /**
+     * Sets the Last-Event-ID HTTP request header reports an EventSource object's last event ID string to the server when the user agent is to reestablish the connection.
+     * @param id the ID
+     * @return this request builder
+     */
+    SseRequest lastEventId(String id);
+
     /**
      * @return the full URL if the request
      */

unirest/src/main/java/kong/unirest/core/SseRequestImpl.java

@@ -39,6 +39,7 @@ public class SseRequestImpl implements SseRequest {
     protected Headers headers = new Headers();
 
 
+
     public SseRequestImpl(Config config, String url) {
         Objects.requireNonNull(config, "Config cannot be null");
         Objects.requireNonNull(url,    "URL cannot be null");
@@ -126,6 +127,11 @@ public SseRequest queryString(Map<String, Object> parameters) {
         return this;
     }
 
+    @Override
+    public SseRequest lastEventId(String id) {
+        return header("Last-Event-ID", id);
+    }
+
     @Override
     public CompletableFuture<Void> connect(SseHandler handler) {
         return config.getClient().sse(this, handler);