fix spotbugs

Author: yanmin

hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/fs/http/client/HttpFSFileSystem.java

@@ -1370,7 +1370,7 @@ public byte[] getXAttr(Path f, String name) throws IOException {
     JSONObject json = (JSONObject) HttpFSUtils.jsonParse(conn);
     Map<String, byte[]> xAttrs = createXAttrMap(
         (JSONArray) json.get(XATTRS_JSON));
-    return xAttrs != null ? xAttrs.get(name) : null;
+    return xAttrs.get(name);
   }
 
   /** Convert xAttrs json to xAttrs map */

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcServer.java

@@ -1087,13 +1087,7 @@ public DatanodeInfo[] getDatanodeReport(DatanodeReportType type)
   DatanodeInfo[] getCachedDatanodeReport(DatanodeReportType type)
       throws IOException {
     try {
-      DatanodeInfo[] dns = this.dnCache.get(type);
-      if (dns == null) {
-        LOG.debug("Get null DN report from cache");
-        dns = getCachedDatanodeReportImpl(type);
-        this.dnCache.put(type, dns);
-      }
-      return dns;
+      return this.dnCache.get(type);
     } catch (ExecutionException e) {
       LOG.error("Cannot get the DN report for {}", type, e);
       Throwable cause = e.getCause();

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services/dev-support/findbugs-exclude.xml

@@ -55,5 +55,10 @@
         <Field name="additional"/>
       </Or>
       <Bug pattern="SE_BAD_FIELD" />
-  </Match>
+    </Match>
+    <Match>
+        <Class name="org.apache.hadoop.yarn.service.ServiceScheduler$1"/>
+        <Method name="load"/>
+        <Bug code="NP" pattern="NP_NONNULL_RETURN_VIOLATION"/>
+    </Match>
 </FindBugsFilter>