Add some missing newlines at the ends of files

core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterIterator.java

@@ -32,4 +32,4 @@ public abstract class UnsafeSorterIterator {
   public abstract int getRecordLength();
 
   public abstract long getKeyPrefix();
-}
+}

core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillReader.java

@@ -86,4 +86,4 @@ public int getRecordLength() {
   public long getKeyPrefix() {
     return keyPrefix;
   }
-}
+}

core/src/test/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorterSuite.java

@@ -180,4 +180,4 @@ public void testSortingOnlyByPartitionId() throws Exception {
     // assert(tempDir.isEmpty)
   }
 
-}
+}

core/src/test/java/org/apache/spark/util/collection/unsafe/sort/UnsafeInMemorySorterSuite.java

@@ -139,4 +139,4 @@ public int compare(long prefix1, long prefix2) {
     }
     assertEquals(dataToSort.length, iterLength);
   }
-}
+}