[SPARK-25576][BUILD][BRANCH-2.2] Fix lint failure

common/unsafe/src/test/java/org/apache/spark/unsafe/types/UTF8StringSuite.java

@@ -63,7 +63,9 @@ public void basicTest() {
     checkBasic("hello", 5); // 5 * 1 byte chars
     checkBasic("大 千 世 界", 7);
     checkBasic("︽﹋％", 3); // 3 * 3 bytes chars
+    // checkstyle.off: AvoidEscapedUnicodeCharacters
     checkBasic("\uD83E\uDD19", 1); // 4 bytes char
+    // checkstyle.on: AvoidEscapedUnicodeCharacters
   }
 
   @Test

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

@@ -174,9 +174,12 @@ public void reset() {
     if (consumer != null) {
       consumer.freeArray(array);
       // the call to consumer.allocateArray may trigger a spill
-      // which in turn access this instance and eventually re-enter this method and try to free the array again.
-      // by setting the array to null and its length to 0 we effectively make the spill code-path a no-op.
-      // setting the array to null also indicates that it has already been de-allocated which prevents a double de-allocation in free().
+      // which in turn access this instance and eventually re-enter this method
+      // and try to free the array again.
+      // By setting the array to null and its length to 0
+      // we effectively make the spill code-path a no-op.
+      // Setting the array to null also indicates that it has already been
+      // de-allocated which prevents a double de-allocation in free().
       array = null;
       usableCapacity = 0;
       pos = 0;

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

@@ -460,7 +460,7 @@ public void testPeakMemoryUsed() throws Exception {
   @Test
   public void testOOMDuringSpill() throws Exception {
     final UnsafeExternalSorter sorter = newSorter();
-    // we assume that given default configuration,
+    // We assume that given default configuration,
     // the size of the data we insert to the sorter (ints)
     // and assuming we shouldn't spill before pointers array is exhausted
     // (memory manager is not configured to throw at this point)
@@ -469,23 +469,28 @@ public void testOOMDuringSpill() throws Exception {
     for (int i = 0; sorter.hasSpaceForAnotherRecord(); ++i) {
       insertNumber(sorter, i);
     }
-    // we expect the next insert to attempt growing the pointerssArray
-    // first allocation is expected to fail, then a spill is triggered which attempts another allocation
+    // We expect the next insert to attempt growing the pointerssArray
+    // first allocation is expected to fail, then a spill is
+    // triggered which attempts another allocation
     // which also fails and we expect to see this OOM here.
     // the original code messed with a released array within the spill code
     // and ended up with a failed assertion.
-    // we also expect the location of the OOM to be org.apache.spark.util.collection.unsafe.sort.UnsafeInMemorySorter.reset
+    // We also expect the location of the OOM to be
+    // org.apache.spark.util.collection.unsafe.sort.UnsafeInMemorySorter.reset
     memoryManager.markconsequentOOM(2);
     try {
       insertNumber(sorter, 1024);
       fail("expected OutOfMmoryError but it seems operation surprisingly succeeded");
     }
-    // we expect an OutOfMemoryError here, anything else (i.e the original NPE is a failure)
+    // We expect an OutOfMemoryError here, anything else
+    // (i.e the original NPE is a failure)
     catch (OutOfMemoryError oom){
       String oomStackTrace = Utils.exceptionString(oom);
-      assertThat("expected OutOfMemoryError in org.apache.spark.util.collection.unsafe.sort.UnsafeInMemorySorter.reset",
-              oomStackTrace,
-              Matchers.containsString("org.apache.spark.util.collection.unsafe.sort.UnsafeInMemorySorter.reset"));
+      assertThat("expected OutOfMemoryError in " +
+        "org.apache.spark.util.collection.unsafe.sort.UnsafeInMemorySorter.reset",
+        oomStackTrace,
+        Matchers.containsString(
+          "org.apache.spark.util.collection.unsafe.sort.UnsafeInMemorySorter.reset"));
     }
   }
 }

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

@@ -183,7 +183,8 @@ public int compare(
     } catch (OutOfMemoryError oom) {
       // as expected
     }
-    // [SPARK-21907] this failed on NPE at org.apache.spark.memory.MemoryConsumer.freeArray(MemoryConsumer.java:108)
+    // [SPARK-21907] this failed on NPE at
+    // org.apache.spark.memory.MemoryConsumer.freeArray(MemoryConsumer.java:108)
     sorter.free();
     // simulate a 'back to back' free.
     sorter.free();

sql/core/src/main/java/org/apache/spark/sql/execution/UnsafeKVExternalSorter.java

@@ -259,7 +259,7 @@ public int compare(
         Object baseObj2,
         long baseOff2,
         int baseLen2) {
-      // Note that since ordering doesn't need the total length of the record, we just pass -1	
+      // Note that since ordering doesn't need the total length of the record, we just pass -1
       // into the row.
       row1.pointTo(baseObj1, baseOff1 + 4, -1);
       row2.pointTo(baseObj2, baseOff2 + 4, -1);