MAPREDUCE-7522. Fix SpotBugs issues in hadoop-mapreduce-client-app module.

Author: slfan1989

hadoop-mapreduce-project/dev-support/findbugs-exclude.xml

@@ -554,4 +554,9 @@
     <Method name="onSuccess" />
     <Bug pattern="NP_PARAMETER_MUST_BE_NONNULL_BUT_MARKED_AS_NULLABLE" />
   </Match>
+
+  <Match><Bug category="EXPERIMENTAL"/></Match>
+  <Match><Bug pattern="AT_.*"/></Match>
+  <Match><Bug pattern="CT_.*"/></Match>
+  <Match><Bug pattern="PA_PUBLIC_PRIMITIVE_ATTRIBUTE"/></Match>
  </FindBugsFilter>