Client.Default - Null pointer exception when receiving an 'empty' response with compression (#2510)

* Client.Default - Null pointer exception when receiving an 'empty' response with compression

* Apply code style

Author: gromspys

core/src/main/java/feign/Client.java

@@ -134,9 +134,9 @@ Response convertResponse(HttpURLConnection connection, Request request) throws I
       } else {
         stream = connection.getInputStream();
       }
-      if (this.isGzip(headers.get(CONTENT_ENCODING))) {
+      if (stream != null && this.isGzip(headers.get(CONTENT_ENCODING))) {
         stream = new GZIPInputStream(stream);
-      } else if (this.isDeflate(headers.get(CONTENT_ENCODING))) {
+      } else if (stream != null && this.isDeflate(headers.get(CONTENT_ENCODING))) {
         stream = new InflaterInputStream(stream);
       }
       return Response.builder()

core/src/test/java/feign/client/AbstractClientTest.java

@@ -419,6 +419,25 @@ public void canSupportGzipOnError() throws Exception {
 
   }
 
+  @Test
+  public void canSupportGzipOnErrorWithoutBody() throws Exception {
+    server.enqueue(new MockResponse().setResponseCode(400)
+        .addHeader("Content-Encoding", "gzip"));
+
+    TestInterface api =
+        newBuilder().target(TestInterface.class, "http://localhost:" + server.getPort());
+
+    try {
+      api.get();
+      fail("Expect FeignException");
+    } catch (FeignException e) {
+      /* verify that the response is unzipped */
+      assertThat(e.responseBody()).isNotEmpty()
+          .map(body -> new String(body.array(), StandardCharsets.UTF_8))
+          .get().isEqualTo("");
+    }
+  }
+
   @Test
   public void canSupportDeflate() throws Exception {
     /* enqueue a zipped response */
@@ -456,6 +475,25 @@ public void canSupportDeflateOnError() throws Exception {
     }
   }
 
+  @Test
+  public void canSupportDeflateOnErrorWithoutBody() throws Exception {
+    server.enqueue(new MockResponse().setResponseCode(400)
+        .addHeader("Content-Encoding", "deflate"));
+
+    TestInterface api =
+        newBuilder().target(TestInterface.class, "http://localhost:" + server.getPort());
+
+    try {
+      api.get();
+      fail("Expect FeignException");
+    } catch (FeignException e) {
+      /* verify that the response is unzipped */
+      assertThat(e.responseBody()).isNotEmpty()
+          .map(body -> new String(body.array(), StandardCharsets.UTF_8))
+          .get().isEqualTo("");
+    }
+  }
+
   @Test
   public void canExceptCaseInsensitiveHeader() throws Exception {
     /* enqueue a zipped response */