code: @Override
      public String matchPredicateOperand(String alias) {
          Objects.requireNonNull(alias, "alias cannot be null");
          // alias.identifier
          return alias + "." + idFieldName;
      }
docs: Gets the MATCH WHERE predicate operand.
  
  @param alias The neo4j {@link Entity} alias in a MATCH statement.
  @return The MATCH WHERE predicate operand.