public static Expression removeDuplicateConjunct(Expression predicate) {
    if (predicate == null) {
      return null;
    }
    Set<Expression> conjuncts = new HashSet<>();
    extractConjuncts(predicate, conjuncts);
    return combineConjuncts(new ArrayList<>(conjuncts));
  }
Combine the given conjuncts into a single expression using "and".

@param conjuncts given conjuncts
@return the expression combined by the given conjuncts
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/analyze/PredicateUtils.java