Add headers to WebhookResponse class (#1043)

Author: seratch

slack-api-client/src/main/java/com/slack/api/Slack.java

@@ -128,6 +128,7 @@ public WebhookResponse send(String url, Payload payload) throws IOException {
         return WebhookResponse.builder()
                 .code(httpResponse.code())
                 .message(httpResponse.message())
+                .headers(httpResponse.headers().toMultimap())
                 .body(body)
                 .build();
     }
@@ -144,6 +145,7 @@ public WebhookResponse send(String url, String payload) throws IOException {
         return WebhookResponse.builder()
                 .code(httpResponse.code())
                 .message(httpResponse.message())
+                .headers(httpResponse.headers().toMultimap())
                 .body(body)
                 .build();
     }

slack-api-client/src/test/java/test_with_remote_apis/IncomingWebhooksTest.java

@@ -26,6 +26,7 @@
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.CoreMatchers.nullValue;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.greaterThan;
 
 @Slf4j
 public class IncomingWebhooksTest {
@@ -291,4 +292,12 @@ public void testInvalidBlocksError() throws Exception {
         assertThat(response.getBody(), is("invalid_blocks"));
         assertThat(response.getCode(), is(400));
     }
+
+    @Test
+    public void headers() throws IOException {
+        WebhookResponse response = slack.send(url, Payload.builder().text("Hello world!").build());
+        assertThat(response.getBody(), is("ok"));
+        assertThat(response.getCode(), is(200));
+        assertThat(response.getHeaders().size(),is(greaterThan(0)));
+    }
 }

slack-api-model/src/main/java/com/slack/api/webhook/WebhookResponse.java

@@ -3,10 +3,14 @@
 import lombok.Builder;
 import lombok.Data;
 
+import java.util.List;
+import java.util.Map;
+
 @Data
 @Builder
 public class WebhookResponse {
     private Integer code;
     private String message;
+    private Map<String, List<String>> headers;
     private String body;
 }