Allow 1xx status codes (#871)

* add support for 1xx status codes in Response

* allow for any status code

Author: maly7

core/src/main/java/feign/Response.java

@@ -45,7 +45,6 @@ public final class Response implements Closeable {
   private final Request request;
 
   private Response(Builder builder) {
-    checkState(builder.status >= 200, "Invalid status code: %s", builder.status);
     checkState(builder.request != null, "original request is required");
     this.status = builder.status;
     this.request = builder.request;

core/src/test/java/feign/ResponseTest.java

@@ -14,6 +14,7 @@
 package feign;
 
 import feign.Request.HttpMethod;
+import org.assertj.core.util.Lists;
 import org.junit.Test;
 import java.util.Arrays;
 import java.util.Collection;
@@ -81,4 +82,28 @@ public void headersAreOptional() {
         .build();
     assertThat(response.headers()).isNotNull().isEmpty();
   }
+
+  @Test
+  public void support1xxStatusCodes() {
+    Response response = Response.builder()
+        .status(103)
+        .request(Request.create(HttpMethod.GET, "/api", Collections.emptyMap(), null, Util.UTF_8))
+        .body((Response.Body) null)
+        .build();
+
+    assertThat(response.status()).isEqualTo(103);
+  }
+
+  @Test
+  public void statusCodesOfAnyValueAreAllowed() {
+    Lists.list(600, 50, 35600).forEach(statusCode -> {
+      Response response = Response.builder()
+          .status(statusCode)
+          .request(Request.create(HttpMethod.GET, "/api", Collections.emptyMap(), null, Util.UTF_8))
+          .body((Response.Body) null)
+          .build();
+
+      assertThat(response.status()).isEqualTo(statusCode);
+    });
+  }
 }