Addendum HADOOP-17770 WASB : Support disabling buffered reads in posi…

…tional reads - Added the invalid SpotBugs warning to findbugs-exclude.xml (#3223)

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

@@ -83,4 +83,17 @@
     <Bug pattern="IS2_INCONSISTENT_SYNC" />
   </Match>
 
+  <!-- This field is instance of BlockBlobInputStream and read(long, byte[], int, int)
+  calls it's Super class method when 'fs.azure.block.blob.buffered.pread.disable'
+  is configured false. Super class FSInputStream's implementation is having
+  proper synchronization.
+  When 'fs.azure.block.blob.buffered.pread.disable' is true, we want a lock free
+  implementation of blob read. Here we don't use any of the InputStream's
+  shared resource (buffer) and also don't change any cursor position etc.
+  So its safe to go with unsynchronized way of read. -->
+  <Match>
+    <Class name="org.apache.hadoop.fs.azure.NativeAzureFileSystem$NativeAzureFsInputStream" />
+    <Field name="in" />
+    <Bug pattern="IS2_INCONSISTENT_SYNC" />
+  </Match>
  </FindBugsFilter>