public List<String> getColumns() {
    return columns;
  }
Applicable columns in this object, when the type is {@link HivePrivilegeObjectType#TABLE_OR_VIEW}
In case of DML read operations, this is the set of columns being used.
Column information is not set for DDL operations and for tables being written into
@return list of applicable columns
ql/src/java/org/apache/hadoop/hive/ql/security/authorization/plugin/HivePrivilegeObject.java