[SPARK-6428] Turn on explicit type checking for public methods.

This builds on my earlier pull requests and turns on the explicit type checking in scalastyle.

Author: Reynold Xin <rxin@databricks.com>

Closes #5342 from rxin/SPARK-6428 and squashes the following commits:

7b531ab [Reynold Xin] import ordering
2d9a8a5 [Reynold Xin] jl
e668b1c [Reynold Xin] override
9b9e119 [Reynold Xin] Parenthesis.
82e0cf5 [Reynold Xin] [SPARK-6428] Turn on explicit type checking for public methods.

2 files changed, 3 insertions, 2 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
index c4da34ae64..ae5ce4cf4c 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
@@ -861,7 +861,7 @@ private[hive] case class MetastoreRelation
   /** An attribute map for determining the ordinal for non-partition columns. */
   val columnOrdinals = AttributeMap(attributes.zipWithIndex)
 
-  override def newInstance() = {
+  override def newInstance(): MetastoreRelation = {
     MetastoreRelation(databaseName, tableName, alias)(table, partitions)(sqlContext)
   }
 }
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 5be09a11ad..077e64133f 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
@@ -659,7 +659,8 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
                   AttributeReference("value", StringType)()), true)
             }
 
-            def matchSerDe(clause: Seq[ASTNode]) = clause match {
+            def matchSerDe(clause: Seq[ASTNode])
+              : (Seq[(String, String)], String, Seq[(String, String)]) = clause match {
               case Token("TOK_SERDEPROPS", propsClause) :: Nil =>
                 val rowFormat = propsClause.map {
                   case Token(name, Token(value, Nil) :: Nil) => (name, value)