@Override
      public RelNode visit(RelNode relNode) {
        // There should never be a TableModify in the calcite plan.
        Validate.isTrue(!(relNode instanceof TableModify));
        return super.visit(relNode);
      }
Translate Calcite plan to Samza stream operators.
@param relRoot Calcite plan in the form of {@link RelRoot}. RelRoot should not include the sink ({@link TableModify})
@param outputSystemStream Sink associated with the Calcite plan.
@param translatorContext Context maintained across translations.
@param queryId query index of the sql statement corresponding to the Calcite plan in multi SQL statement scenario
               starting with index 0.
samza-sql/src/main/java/org/apache/samza/sql/translator/QueryTranslator.java