Allowlist known blocking methods from BlockHound (#2897)

* Allow-list known blocking methods from BlockHound

There are two known occurrences where the SDK may currently block from
within a Netty EventLoop:

1. #2145
2. #2360

Allowing BlockHound to forbid these operations may fail existing
integration and stability tests. While we have outstanding issues to fix
these items, until they are resolved, we need to allow our existing
integration tests to continue to pass. We should explicitly allow-list
these methods so that they do not interfere with existing tests and so
that we maintain visibility on future regression detection.

Author: Bennett-Lynch

test/service-test-utils/src/main/java/software/amazon/awssdk/testutils/service/BlockHoundAllowlist.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.awssdk.testutils.service;
+
+import reactor.blockhound.BlockHound;
+import reactor.blockhound.integration.BlockHoundIntegration;
+
+/**
+ * Implements {@link BlockHoundIntegration} to explicitly allow SDK calls that are known to be blocking. Some calls (with an
+ * associated tracking issue) may wrongly block, but we allow-list them so that existing integration tests will continue to pass
+ * and so that we preserve visibility on future regression detection.
+ * <p>
+ * https://github.com/reactor/BlockHound/blob/master/docs/custom_integrations.md
+ */
+public class BlockHoundAllowlist implements BlockHoundIntegration {
+    @Override
+    public void applyTo(BlockHound.Builder builder) {
+        // https://github.com/aws/aws-sdk-java-v2/issues/2145
+        builder.allowBlockingCallsInside(
+            "software.amazon.awssdk.http.nio.netty.internal.BetterSimpleChannelPool",
+            "close"
+        );
+
+        // https://github.com/aws/aws-sdk-java-v2/issues/2360
+        builder.allowBlockingCallsInside(
+            "software.amazon.awssdk.auth.credentials.InstanceProfileCredentialsProvider",
+            "getToken"
+        );
+    }
+}

test/service-test-utils/src/main/resources/META-INF/services/reactor.blockhound.integration.BlockHoundIntegration

@@ -0,0 +1,16 @@
+#
+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License").
+# You may not use this file except in compliance with the License.
+# A copy of the License is located at
+#
+#  http://aws.amazon.com/apache2.0
+#
+# or in the "license" file accompanying this file. This file is distributed
+# on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+# express or implied. See the License for the specific language governing
+# permissions and limitations under the License.
+#
+
+software.amazon.awssdk.testutils.service.BlockHoundAllowlist