[SPARK-16372][MLLIB] Retag RDD to tallSkinnyQR of RowMatrix

## What changes were proposed in this pull request?

The following Java code because of type erasing:

```Java
JavaRDD<Vector> rows = jsc.parallelize(...);
RowMatrix mat = new RowMatrix(rows.rdd());
QRDecomposition<RowMatrix, Matrix> result = mat.tallSkinnyQR(true);
```

We should use retag to restore the type to prevent the following exception:

```Java
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Lorg.apache.spark.mllib.linalg.Vector;
```

## How was this patch tested?

Java unit test

Author: Xusen Yin <yinxusen@gmail.com>

Closes #14051 from yinxusen/SPARK-16372.

1 files changed, 44 insertions, 0 deletions

diff --git a/mllib/src/test/java/org/apache/spark/mllib/linalg/distributed/JavaRowMatrixSuite.java b/mllib/src/test/java/org/apache/spark/mllib/linalg/distributed/JavaRowMatrixSuite.java
new file mode 100644
index 0000000000..c01af40549
--- /dev/null
+++ b/mllib/src/test/java/org/apache/spark/mllib/linalg/distributed/JavaRowMatrixSuite.java
@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.mllib.linalg.distributed;
+
+import java.util.Arrays;
+
+import org.junit.Test;
+
+import org.apache.spark.SharedSparkSession;
+import org.apache.spark.api.java.JavaRDD;
+import org.apache.spark.mllib.linalg.Matrix;
+import org.apache.spark.mllib.linalg.QRDecomposition;
+import org.apache.spark.mllib.linalg.Vector;
+import org.apache.spark.mllib.linalg.Vectors;
+
+public class JavaRowMatrixSuite extends SharedSparkSession {
+
+  @Test
+  public void rowMatrixQRDecomposition() {
+    Vector v1 = Vectors.dense(1.0, 10.0, 100.0);
+    Vector v2 = Vectors.dense(2.0, 20.0, 200.0);
+    Vector v3 = Vectors.dense(3.0, 30.0, 300.0);
+
+    JavaRDD<Vector> rows = jsc.parallelize(Arrays.asList(v1, v2, v3), 1);
+    RowMatrix mat = new RowMatrix(rows.rdd());
+
+    QRDecomposition<RowMatrix, Matrix> result = mat.tallSkinnyQR(true);
+  }
+}