We have introduced a new feature that allows the use of DisMax queries for default field searches. The following changes were made to the codebase: - Added new configuration keys for DisMax query parameters in `fess_config.properties`. - Modified the `FessConfig` interface to include new keys for DisMax query settings. - Updated the `QueryCommand` and `TermQueryCommand` classes to support DisMax queries. - Created a new `DefaultQueryBuilder` class to manage different query types.