Improve custom schema.

Author: wangyum

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRDD.scala

@@ -82,8 +82,8 @@ object JDBCRDD extends Logging {
    * @return A Catalyst schema corresponding to columns in the given order.
    */
   private def pruneSchema(schema: StructType, columns: Array[String]): StructType = {
-     val fieldMap = Map(schema.fields.map(x => x.name -> x): _*)
-     new StructType(columns.map(name => fieldMap(name)))
+    val fieldMap = Map(schema.fields.map(x => x.name -> x): _*)
+    new StructType(columns.map(name => fieldMap(name)))
   }
 
   /**