Example - Aster Execution Engine

...
Distribution inDistribution = null;
ListColumnDefinition inDistrCols = null;
DistributionType inDistrType = null;

// read in distribution
if (planInputInfo.hasDistribution())
{
  inDistribution = planInputInfo.getDistribution();
  inDistrCols = inDistribution.getDistributionColumns();
  inDistrType = inDistribution.getDistributionType();
}
...
// Input distribution passes through as output distribution,
// specified in the completedPlanningContract method.
Distribution outDistribution = null;
...
{
  outDistribution = inDistribution;
}
else if (planInputInfo.hasDistribution())
{
...
}
...
  outDistrType = inDistrType;
}
  outDistribution = new Distribution.Builder()
    .setDistributionColumns(outDistrCols)
    .setDistributionType(outDistrType)
    .toDistribution();
}
...
planOutputInfo = new PlanOutputInfo.Builder()
  .setDistribution(outDistribution)
...

For full context, see Examples.