HADOOP-19717. Resolve build error caused by missing Checker Framework (NonNull not recognized).

Author: slfan1989

hadoop-cloud-storage-project/hadoop-tos/src/main/java/org/apache/hadoop/fs/tosfs/util/Iterables.java

@@ -19,7 +19,7 @@
 package org.apache.hadoop.fs.tosfs.util;
 
 import org.apache.hadoop.util.Preconditions;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import org.apache.hadoop.thirdparty.org.checkerframework.checker.nullness.qual.Nullable;
 
 import java.util.Iterator;
 import java.util.NoSuchElementException;

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

@@ -99,6 +99,7 @@
 import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ListeningExecutorService;
 import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.MoreExecutors;
 import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ThreadFactoryBuilder;
+import org.apache.hadoop.thirdparty.org.checkerframework.checker.nullness.qual.NonNull;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.crypto.CryptoProtocolVersion;
 import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedEntries;
@@ -213,7 +214,6 @@
 import org.apache.hadoop.tools.protocolPB.GetUserMappingsProtocolPB;
 import org.apache.hadoop.tools.protocolPB.GetUserMappingsProtocolServerSideTranslatorPB;
 import org.apache.hadoop.util.ReflectionUtils;
-import org.checkerframework.checker.nullness.qual.NonNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;