make URIStatus Serializable

Author: chenruotao

core/common/src/main/java/alluxio/client/file/URIStatus.java

@@ -22,6 +22,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
 
+import java.io.Serializable;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -37,7 +38,7 @@
  */
 @PublicApi
 @ThreadSafe
-public class URIStatus {
+public class URIStatus implements Serializable {
   /** Information about this URI retrieved from Alluxio master. */
   private final FileInfo mInfo;
   /** Context associated with this URI, possibly set by other external engines (e.g., presto). */