Shim to aid migration of ByteString to a new package
[CALCITE-535] Support skip overwrite in hydromatic-resource
[CALCITE-513] Support for grouping sets in AggregateProjectMergeRule (Jesus Camacho Rodriguez)

Close apache/incubator-calcite#29
[CALCITE-532] Support for grouping sets in AggregateFilterTransposeRule (Jesus Camacho Rodriguez)

Close apache/incubator-calcite#33
[CALCITE-533] Support for grouping sets in FilterAggregateTransposeRule (Jesus Camacho Rodriguez)

Close apache/incubator-calcite#34
[CALCITE-479] Migrate RelNode.getChildExps to RelNode.accept(RexShuttle)

Close apache/incubator-calcite#31