JdbcTemplateの照会系の結果をBeanに詰めるにはBeanPropertyRowMapperが必要
とりあえずはそんな理解です。
件のクラスのJavadoc見ると、以下のように記載されていますね。
RowMapper implementation that converts a row into a new instance of the specified mapped target class. The mapped target class must be a top-level class and it must have a default or no-arg constructor. Column values are mapped based on matching the column name as obtained from result set metadata to public setters for the corresponding properties. The names are matched either directly or by transforming a name separating the parts with underscores to the same name using "camel" case.
オチは特にない。深く見てはいないです。