An SBE message provides access to message fields via its methods.
To get/set a field value, use the corresponding method of the strongly typed message class.
The naming convention for setters is fieldName(..).
To set the value of the optional field to null, use the fieldName(nullOpt) method.
The naming convention for getters is fieldName().
Getters for optional fields return true if the value is present, otherwise - false.