code: private void validateTableOptionAgingField(TableDefinition tableDef, String optValue) {
          FieldDefinition agingFieldDef = tableDef.getFieldDef(optValue);
          Utils.require(agingFieldDef != null,
                        "Aging field has not been defined: " + optValue);
          assert agingFieldDef != null;   // Make FindBugs happy
          Utils.require(agingFieldDef.getType() == FieldType.TIMESTAMP,
                        "Aging field must be a timestamp field: " + optValue);
          Utils.require(tableDef.getOption(CommonDefs.OPT_RETENTION_AGE) != null,
                        "Option 'aging-field' requires option 'retention-age'");
      }
docs: Validate the table option "aging-field".