code: Delta newUnpublishedDatabusEventUpdate(String tableName, String updateType, String datetime) {
          return Deltas.mapBuilder()
                  .update("tables", Deltas.setBuilder().add(ImmutableMap.of("table", tableName, "date", datetime, "event", updateType)).build())
                  .build();
      }
docs: Delta for storing the unpublished databus events.