[SPARK-2924] remove default args to overloaded methods

Not supported in Scala 2.11. Split them into separate methods instead.

Author: Anand Avati <avati@redhat.com>

Closes #1704 from avati/SPARK-1812-default-args and squashes the following commits:

3e3924a [Anand Avati] SPARK-1812: Add Mima excludes for the broken ABI
901dfc7 [Anand Avati] SPARK-1812: core - Fix overloaded methods with default arguments
07f00af [Anand Avati] SPARK-1812: streaming - Fix overloaded methods with default arguments

core/src/main/scala/org/apache/spark/ui/JettyUtils.scala

@@ -93,7 +93,7 @@ private[spark] object JettyUtils extends Logging {
   def createServletHandler(
       path: String,
       servlet: HttpServlet,
-      basePath: String = ""): ServletContextHandler = {
+      basePath: String): ServletContextHandler = {
     val prefixedPath = attachPrefix(basePath, path)
     val contextHandler = new ServletContextHandler
     val holder = new ServletHolder(servlet)

project/MimaExcludes.scala

@@ -117,6 +117,9 @@ object MimaExcludes {
           ) ++
           Seq( // new Vector methods in MLlib (binary compatible assuming users do not implement Vector)
             ProblemFilters.exclude[MissingMethodProblem]("org.apache.spark.mllib.linalg.Vector.copy")
+          ) ++
+          Seq ( // Scala 2.11 compatibility fix
+            ProblemFilters.exclude[MissingMethodProblem]("org.apache.spark.streaming.StreamingContext.<init>$default$2")
           )
         case v if v.startsWith("1.0") =>
           Seq(

streaming/src/main/scala/org/apache/spark/streaming/StreamingContext.scala

@@ -98,9 +98,15 @@ class StreamingContext private[streaming] (
    * @param hadoopConf Optional, configuration object if necessary for reading from
    *                   HDFS compatible filesystems
    */
-  def this(path: String, hadoopConf: Configuration = new Configuration) =
+  def this(path: String, hadoopConf: Configuration) =
     this(null, CheckpointReader.read(path, new SparkConf(), hadoopConf).get, null)
 
+  /**
+   * Recreate a StreamingContext from a checkpoint file.
+   * @param path Path to the directory that was specified as the checkpoint directory
+   */
+  def this(path: String) = this(path, new Configuration)
+
   if (sc_ == null && cp_ == null) {
     throw new Exception("Spark Streaming cannot be initialized with " +
       "both SparkContext and checkpoint as null")