suppress inconsistent sync spotbug warning

Author: ahmarsuhail

hadoop-tools/hadoop-aws/dev-support/findbugs-exclude.xml

@@ -64,6 +64,11 @@
     <Field name="futurePool"/>
     <Bug pattern="IS2_INCONSISTENT_SYNC"/>
   </Match>
+  <Match>
+    <Class name="org.apache.hadoop.fs.s3a.S3AFileSystem"/>
+    <Field name="s3AsyncClient"/>
+    <Bug pattern="IS2_INCONSISTENT_SYNC"/>
+  </Match>
   <Match>
     <Class name="org.apache.hadoop.fs.s3a.s3guard.S3GuardTool$BucketInfo"/>
     <Method name="run"/>