code: public static double[] doubleArrayWrappedOrCopy(CollectionNumber coll) {
          double[] array = wrappedDoubleArray(coll);
          if (array != null) {
              return array;
          }
          return doubleArrayCopyOf(coll);
      }
docs: Returns either the wrapped array (if exists and matches the type)
  or a copy - USE WITH CAUTION AS IT MAY EXPOSE THE INTERNAL STATE
  OF THE COLLECTION.
  
  @param coll the collection
  @return the array