GroupProjection groupProjection = new GroupProjection();
groupProjection.keys(Arrays.<DataTypeSymbol>asList(new InputColumn(1, DataTypes.STRING)));
groupProjection.values(Arrays.asList(
new Aggregation(
countAggregation.info(),
ImmutableList.<Symbol>of(new InputColumn(0)),
Aggregation.Step.PARTIAL,
Aggregation.Step.FINAL
)
));