Change Accumulators to private[spark] instead of adding mima exclude to get around false positive in mima tests

Author: Nathan Kronenfeld

core/src/main/scala/org/apache/spark/Accumulators.scala

@@ -279,7 +279,7 @@ object AccumulatorParam {
 
 // TODO: The multi-thread support in accumulators is kind of lame; check
 // if there's a more intuitive way of doing it right
-private object Accumulators {
+private[spark] object Accumulators {
   // TODO: Use soft references? => need to make readObject work properly then
   val originals = Map[Long, Accumulable[_, _]]()
   val localAccums = new ThreadLocal[Map[Long, Accumulable[_, _]]]() {

project/MimaExcludes.scala

@@ -53,10 +53,6 @@ object MimaExcludes {
               "org.apache.spark.mllib.linalg.Matrices.randn"),
             ProblemFilters.exclude[MissingMethodProblem](
               "org.apache.spark.mllib.linalg.Matrices.rand")
-          ) ++ Seq(
-            // SPARK-4772
-            ProblemFilters.exclude[IncompatibleResultTypeProblem](
-              "org.apache.spark.Accumulators.localAccums")
           )
 
         case v if v.startsWith("1.2") =>