@Override
    public void setException(Throwable ex) {
      exception =
          (ex instanceof FunctionException) ? (FunctionException) ex : new FunctionException(ex);
    }
Aborts any further collection of results and forwards the cancellation to the members
involved in the export.
geode-core/src/main/java/org/apache/geode/internal/cache/snapshot/WindowedExporter.java