HADOOP-15831. Include modificationTime in the toString method of CopyListingFileStatus.

Contributed by Ted Yu.

hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/CopyListingFileStatus.java

@@ -405,10 +405,11 @@ public final class CopyListingFileStatus implements Writable {
   public String toString() {
     StringBuilder sb = new StringBuilder(super.toString());
     sb.append('{');
-    sb.append(this.getPath().toString());
+    sb.append(this.getPath() == null ? "" : this.getPath().toString());
     sb.append(" length = ").append(this.getLen());
     sb.append(" aclEntries = ").append(aclEntries);
     sb.append(", xAttrs = ").append(xAttrs);
+    sb.append(", modTime = ").append(modificationTime);
     if (isSplit()) {
       sb.append(", chunkOffset = ").append(this.getChunkOffset());
       sb.append(", chunkLength = ").append(this.getChunkLength());

hadoop-tools/hadoop-distcp/src/test/java/org/apache/hadoop/tools/TestCopyListingFileStatus.java

@@ -31,6 +31,16 @@ import static org.junit.Assert.assertEquals;
  */
 public class TestCopyListingFileStatus {
 
+  @Test
+  public void testToString() {
+    CopyListingFileStatus src = new CopyListingFileStatus(
+        4344L, false, 2, 512 << 20, 1234L, 5678L, new FsPermission((short)0512),
+        "dingo", "yaks", new Path("hdfs://localhost:4344"));
+    src.toString();
+    src = new CopyListingFileStatus();
+    src.toString();
+  }
+
   @Test
   public void testCopyListingFileStatusSerialization() throws Exception {
     CopyListingFileStatus src = new CopyListingFileStatus(