[SPARK-9118] [ML] Implement IntArrayParam in mllib

Implement IntArrayParam in mllib

Author: Rekha Joshi <rekhajoshm@gmail.com>
Author: Joshi <rekhajoshm@gmail.com>

Closes apache#7481 from rekhajoshm/SPARK-9118 and squashes the following commits:

d3b1766 [Joshi] Implement IntArrayParam
0be142d [Rekha Joshi] Merge pull request #3 from apache/master
106fd8e [Rekha Joshi] Merge pull request #2 from apache/master
e3677c9 [Rekha Joshi] Merge pull request #1 from apache/master

mllib/src/main/scala/org/apache/spark/ml/param/params.scala

@@ -295,6 +295,22 @@ class DoubleArrayParam(parent: Params, name: String, doc: String, isValid: Array
     w(value.asScala.map(_.asInstanceOf[Double]).toArray)
 }
 
+/**
+ * :: DeveloperApi ::
+ * Specialized version of [[Param[Array[Int]]]] for Java.
+ */
+@DeveloperApi
+class IntArrayParam(parent: Params, name: String, doc: String, isValid: Array[Int] => Boolean)
+  extends Param[Array[Int]](parent, name, doc, isValid) {
+
+  def this(parent: Params, name: String, doc: String) =
+    this(parent, name, doc, ParamValidators.alwaysTrue)
+
+  /** Creates a param pair with a [[java.util.List]] of values (for Java and Python). */
+  def w(value: java.util.List[java.lang.Integer]): ParamPair[Array[Int]] =
+    w(value.asScala.map(_.asInstanceOf[Int]).toArray)
+}
+
 /**
  * :: Experimental ::
  * A param and its value.