[SQL] Tighten up visibility for JavaDoc.

I went through all the JavaDocs and tightened up visibility.

Author: Reynold Xin <rxin@databricks.com>

Closes #6526 from rxin/sql-1.4-visibility-for-docs and squashes the following commits:

bc37d1e [Reynold Xin] Tighten up visibility for JavaDoc.

8 files changed, 32 insertions, 14 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
index 994c5202c1..eb3c58c37f 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
@@ -313,7 +313,7 @@ object Decimal {
   // See scala.math's Numeric.scala for examples for Scala's built-in types.
 
   /** Common methods for Decimal evidence parameters */
-  trait DecimalIsConflicted extends Numeric[Decimal] {
+  private[sql] trait DecimalIsConflicted extends Numeric[Decimal] {
     override def plus(x: Decimal, y: Decimal): Decimal = x + y
     override def times(x: Decimal, y: Decimal): Decimal = x * y
     override def minus(x: Decimal, y: Decimal): Decimal = x - y
@@ -327,12 +327,12 @@ object Decimal {
   }
 
   /** A [[scala.math.Fractional]] evidence parameter for Decimals. */
-  object DecimalIsFractional extends DecimalIsConflicted with Fractional[Decimal] {
+  private[sql] object DecimalIsFractional extends DecimalIsConflicted with Fractional[Decimal] {
     override def div(x: Decimal, y: Decimal): Decimal = x / y
   }
 
   /** A [[scala.math.Integral]] evidence parameter for Decimals. */
-  object DecimalAsIfIntegral extends DecimalIsConflicted with Integral[Decimal] {
+  private[sql] object DecimalAsIfIntegral extends DecimalIsConflicted with Integral[Decimal] {
     override def quot(x: Decimal, y: Decimal): Decimal = x / y
     override def rem(x: Decimal, y: Decimal): Decimal = x % y
   }
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/DecimalType.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/DecimalType.scala
index 0f8cecd28f..407dc27326 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/DecimalType.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/DecimalType.scala
@@ -82,12 +82,12 @@ case class DecimalType(precisionInfo: Option[PrecisionInfo]) extends FractionalT
 object DecimalType {
   val Unlimited: DecimalType = DecimalType(None)
 
-  object Fixed {
+  private[sql] object Fixed {
     def unapply(t: DecimalType): Option[(Int, Int)] =
       t.precisionInfo.map(p => (p.precision, p.scale))
   }
 
-  object Expression {
+  private[sql] object Expression {
     def unapply(e: Expression): Option[(Int, Int)] = e.dataType match {
       case t: DecimalType => t.precisionInfo.map(p => (p.precision, p.scale))
       case _ => None
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/SQLUserDefinedType.java b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/SQLUserDefinedType.java
index a64d2bb7cd..df64a878b6 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/SQLUserDefinedType.java
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/SQLUserDefinedType.java
@@ -24,11 +24,11 @@ import org.apache.spark.annotation.DeveloperApi;
 /**
  * ::DeveloperApi::
  * A user-defined type which can be automatically recognized by a SQLContext and registered.
- *
+ * <p>
  * WARNING: This annotation will only work if both Java and Scala reflection return the same class
  *          names (after erasure) for the UDT.  This will NOT be the case when, e.g., the UDT class
  *          is enclosed in an object (a singleton).
- *
+ * <p>
  * WARNING: UDTs are currently only supported from Scala.
  */
 // TODO: Should I used @Documented ?
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala b/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala
index 516ba2ac23..c4ceb0c173 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala
@@ -40,22 +40,22 @@ private[sql] object GroupedData {
   /**
    * The Grouping Type
    */
-  trait GroupType
+  private[sql] trait GroupType
 
   /**
    * To indicate it's the GroupBy
    */
-  object GroupByType extends GroupType
+  private[sql] object GroupByType extends GroupType
 
   /**
    * To indicate it's the CUBE
    */
-  object CubeType extends GroupType
+  private[sql] object CubeType extends GroupType
 
   /**
    * To indicate it's the ROLLUP
    */
-  object RollupType extends GroupType
+  private[sql] object RollupType extends GroupType
 }
 
 /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala b/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala
index d4003b2d9c..e9b60841fc 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/expressions/Window.scala
@@ -79,3 +79,20 @@ object Window {
   }
 
 }
+
+/**
+ * :: Experimental ::
+ * Utility functions for defining window in DataFrames.
+ *
+ * {{{
+ *   // PARTITION BY country ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
+ *   Window.partitionBy("country").orderBy("date").rowsBetween(Long.MinValue, 0)
+ *
+ *   // PARTITION BY country ORDER BY date ROWS BETWEEN 3 PRECEDING AND 3 FOLLOWING
+ *   Window.partitionBy("country").orderBy("date").rowsBetween(-3, 3)
+ * }}}
+ *
+ * @since 1.4.0
+ */
+@Experimental
+class Window private()  // So we can see Window in JavaDoc.
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala b/sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala
index c06026e042..b1b997c030 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/sources/interfaces.scala
@@ -93,7 +93,7 @@ trait SchemaRelationProvider {
 }
 
 /**
- * ::DeveloperApi::
+ * ::Experimental::
  * Implemented by objects that produce relations for a specific kind of data source
  * with a given schema and partitioned columns.  When Spark SQL is given a DDL operation with a
  * USING clause specified (to specify the implemented [[HadoopFsRelationProvider]]), a user defined
@@ -115,6 +115,7 @@ trait SchemaRelationProvider {
  *
  * @since 1.4.0
  */
+@Experimental
 trait HadoopFsRelationProvider {
   /**
    * Returns a new base relation with the given parameters, a user defined schema, and a list of
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
index 3915ee8356..253bf11252 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
@@ -57,7 +57,7 @@ private[hive] case object NativePlaceholder extends LogicalPlan {
   override def output: Seq[Attribute] = Seq.empty
 }
 
-case class CreateTableAsSelect(
+private[hive] case class CreateTableAsSelect(
     tableDesc: HiveTable,
     child: LogicalPlan,
     allowExisting: Boolean) extends UnaryNode with Command {
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ReflectionMagic.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ReflectionMagic.scala
index c600b158c5..4d053ae42c 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ReflectionMagic.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ReflectionMagic.scala
@@ -30,7 +30,7 @@ private[client] object ReflectionException {
 /**
  * Provides implicit functions on any object for calling methods reflectively.
  */
-protected trait ReflectionMagic {
+private[client] trait ReflectionMagic {
     /** code for InstanceMagic
         println(
     (1 to 22).map { n =>