Fix SynchronizationLockException exception when using IMDS for credentials (#4211)

Author: normj

generator/.DevConfigs/3f64412c-8c12-48ef-a8d6-11747964c162.json

@@ -0,0 +1,9 @@
+{
+  "core": {
+    "updateMinimum": true,
+    "type": "patch",
+    "changeLogMessages": [
+      "Fix SynchronizationLockException exception when using IMDS for credentials (https://github.com/aws/aws-sdk-net/issues/4199)"
+    ]
+  }
+}