public static List<FieldSchema> getFieldSchemasFromColumnList(
      List<ExprNodeDesc> cols, List<String> outputColumnNames, int start,
      String fieldPrefix) {
    List<FieldSchema> schemas = new ArrayList<>(cols.size());
    for (int i = 0; i < cols.size(); i++) {
      schemas.add(HiveMetaStoreUtils.getFieldSchemaFromTypeInfo(fieldPrefix
          + outputColumnNames.get(i + start), cols.get(i).getTypeInfo()));
    }
    return schemas;
  }
Convert the ColumnList to FieldSchema list.
ql/src/java/org/apache/hadoop/hive/ql/plan/PlanUtils.java