ResultSetResourceMappingResolver doesn't get the boost value from the ColumnToPropertyMapping and put that into the resource mapping. Therefore that boost value is never used.
The following code in ResultSetResourceMappingResolver .generateResourceProperyMapping fixes this:
if (mapping.getBoost() > 0.0f) {
sb.append("boost=\"").append(mapping.getBoost()).append("\"").append(" ");
}