[SPARK-7176] [ML] Add validation functionality to Param

Main change: Added isValid field to Param.  Modified all usages to use isValid when relevant.  Added helper methods in ParamValidate.

Also overrode Params.validate() in:
* CrossValidator + model
* Pipeline + model

I made a few updates for the elastic net patch:
* I changed "tol" to "convergenceTol"
* I added some documentation

This PR is Scala + Java only.  Python will be in a follow-up PR.

CC: mengxr

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #5740 from jkbradley/enforce-validate and squashes the following commits:

ad9c6c1 [Joseph K. Bradley] re-generated sharedParams after merging with current master
76415e8 [Joseph K. Bradley] reverted convergenceTol to tol
af62f4b [Joseph K. Bradley] Removed changes to SparkBuild, python linalg.  Fixed test failures.  Renamed ParamValidate to ParamValidators.  Removed explicit type from ParamValidators calls where possible.
bb2665a [Joseph K. Bradley] merged with elastic net pr
ecda302 [Joseph K. Bradley] fix rat tests, plus add a little doc
6895dfc [Joseph K. Bradley] small cleanups
069ac6d [Joseph K. Bradley] many cleanups
928fb84 [Joseph K. Bradley] Maybe done
a910ac7 [Joseph K. Bradley] still workin
6d60e2e [Joseph K. Bradley] Still workin
b987319 [Joseph K. Bradley] Partly done with adding checks, but blocking on adding checking functionality to Param
dbc9fb2 [Joseph K. Bradley] merged with master.  enforcing Params.validate

1 files changed, 8 insertions, 6 deletions

diff --git a/examples/src/main/java/org/apache/spark/examples/ml/JavaDeveloperApiExample.java b/examples/src/main/java/org/apache/spark/examples/ml/JavaDeveloperApiExample.java
index eaf00d09f5..46377a99c4 100644
--- a/examples/src/main/java/org/apache/spark/examples/ml/JavaDeveloperApiExample.java
+++ b/examples/src/main/java/org/apache/spark/examples/ml/JavaDeveloperApiExample.java
@@ -28,7 +28,6 @@ import org.apache.spark.ml.classification.Classifier;
 import org.apache.spark.ml.classification.ClassificationModel;
 import org.apache.spark.ml.param.IntParam;
 import org.apache.spark.ml.param.ParamMap;
-import org.apache.spark.ml.param.Params;
 import org.apache.spark.ml.param.Params$;
 import org.apache.spark.mllib.linalg.BLAS;
 import org.apache.spark.mllib.linalg.Vector;
@@ -100,11 +99,12 @@ public class JavaDeveloperApiExample {
 /**
  * Example of defining a type of {@link Classifier}.
  *
- * NOTE: This is private since it is an example.  In practice, you may not want it to be private.
+ * Note: Some IDEs (e.g., IntelliJ) will complain that this will not compile due to
+ *       {@link org.apache.spark.ml.param.Params#set} using incompatible return types.
+ *       However, this should still compile and run successfully.
  */
 class MyJavaLogisticRegression
-    extends Classifier<Vector, MyJavaLogisticRegression, MyJavaLogisticRegressionModel>
-    implements Params {
+    extends Classifier<Vector, MyJavaLogisticRegression, MyJavaLogisticRegressionModel> {
 
   /**
    * Param for max number of iterations
@@ -145,10 +145,12 @@ class MyJavaLogisticRegression
 /**
  * Example of defining a type of {@link ClassificationModel}.
  *
- * NOTE: This is private since it is an example.  In practice, you may not want it to be private.
+ * Note: Some IDEs (e.g., IntelliJ) will complain that this will not compile due to
+ *       {@link org.apache.spark.ml.param.Params#set} using incompatible return types.
+ *       However, this should still compile and run successfully.
  */
 class MyJavaLogisticRegressionModel
-    extends ClassificationModel<Vector, MyJavaLogisticRegressionModel> implements Params {
+    extends ClassificationModel<Vector, MyJavaLogisticRegressionModel> {
 
   private MyJavaLogisticRegression parent_;
   public MyJavaLogisticRegression parent() { return parent_; }