Allow retry when UrlConnectionHttpClient encounters a NullPointerException wrapped in RuntimeException

.changes/next-release/bugfix-UrlConnectionClient-4dd3b0c.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "Url Connection Client",
+    "contributor": "",
+    "description": "Handle unhandled NullPointerException wrapped in RuntimeException when underlying connection fails with URL Connection HTTP Client"
+}

http-clients/url-connection-client/src/main/java/software/amazon/awssdk/http/urlconnection/UrlConnectionHttpClient.java

@@ -366,6 +366,11 @@ private <T> Optional<T> getAndHandle100Bug(Supplier<T> supplier, boolean failOn1
             try {
                 return Optional.ofNullable(supplier.get());
             } catch (RuntimeException e) {
+                if (e.getCause() instanceof NullPointerException) {
+                    throw new UncheckedIOException(new IOException(
+                        "Unexpected RuntimeException wrapping NullPointerException from HttpURLConnection", e));
+                }
+
                 if (!exceptionCausedBy100HandlingBug(e)) {
                     throw e;
                 }
@@ -431,6 +436,12 @@ private static int getResponseCodeSafely(HttpURLConnection connection) throws IO
                 return connection.getResponseCode();
             } catch (NullPointerException e) {
                 throw new IOException("Unexpected NullPointerException when trying to read response from HttpURLConnection", e);
+            } catch (RuntimeException e) {
+                if (e.getCause() instanceof NullPointerException) {
+                    throw new IOException("Unexpected RuntimeException wrapping NullPointerException when trying to "
+                                          + "read response from HttpURLConnection", e);
+                }
+                throw e;
             }
         }
 

http-clients/url-connection-client/src/test/java/software/amazon/awssdk/http/urlconnection/UrlConnectionHttpClientWithCustomCreateWireMockTest.java

@@ -21,6 +21,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.UncheckedIOException;
 import java.net.HttpURLConnection;
 import java.net.ProtocolException;
 import java.net.URL;
@@ -75,6 +76,46 @@
             .hasCauseInstanceOf(NullPointerException.class);
     }
 
+    @Test
+    public void testGetResponseCodeRuntimeExceptionWrappingNpeIsWrappedAsIo() throws Exception {
+        connectionInterceptor = safeFunction(connection -> new DelegateHttpURLConnection(connection) {
+            @Override
+            public int getResponseCode() {
+                throw new RuntimeException(new NullPointerException("this.http is null"));
+            }
+        });
+
+        assertThatThrownBy(() -> testForResponseCode(HttpURLConnection.HTTP_OK))
+            .isInstanceOf(IOException.class)
+            .hasCauseInstanceOf(RuntimeException.class);
+    }
+
+    @Test
+    public void testGetOutputStreamRuntimeExceptionWrappingNpeIsWrappedAsIo() throws Exception {
+        connectionInterceptor = safeFunction(connection -> new DelegateHttpURLConnection(connection) {
+            @Override
+            public OutputStream getOutputStream() {
+                throw new RuntimeException(new NullPointerException("this.http is null"));
+            }
+        });
+
+        assertThatThrownBy(() -> testForResponseCode(HttpURLConnection.HTTP_OK))
+            .isInstanceOf(UncheckedIOException.class);
+    }
+
+    @Test
+    public void testGetInputStreamRuntimeExceptionWrappingNpeIsWrappedAsIo() throws Exception {
+        connectionInterceptor = safeFunction(connection -> new DelegateHttpURLConnection(connection) {
+            @Override
+            public InputStream getInputStream() {
+                throw new RuntimeException(new NullPointerException("this.http is null"));
+            }
+        });
+
+        assertThatThrownBy(() -> testForResponseCode(HttpURLConnection.HTTP_OK))
+            .isInstanceOf(UncheckedIOException.class);
+    }
+
     private class DelegateHttpURLConnection extends HttpURLConnection {
         private final HttpURLConnection delegate;