Returned type of Broadcast variable is byte array

[Stephen Boesch]

As a template for creating a broadcast variable, the following code snippet
within mllib was used:

    val bcIdf = dataset.context.broadcast(idf)
    dataset.mapPartitions { iter =>
      val thisIdf = bcIdf.value


The new code follows that model:

import org.apache.spark.mllib.linalg.{Vector => MVector}
  ..
    assert(crows.isInstanceOf[Array[MVector]])
    val bcRows = sc.broadcast(crows)
    val GU = mat.rows.zipWithIndex.mapPartitions { case dataIter =>
        val arrayVect = bcRows.value         // bcRows.value is seen in
debugger to be of type Array[Byte] .. ??

That last line is unhappy:

   java.lang.ClassCastException: [B cannot be cast to
[Lorg.apache.spark.mllib.linalg.Vector;

So the compiler is aware that the return type of the broadcast "value"
method should be an array of vector (which it should). However the actual
type is Array[Byte].   Any insights on this?