@Override
      public int hashCode() {
        int result = labels.hashCode();
        result = 31 * result + navigation.hashCode();
        return result;
      }
@return the common supertype between the value type and subquery type
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/analyzer/ExpressionAnalyzer.java