question: gets the value of the position property . this accessor method returns a reference to the live list , not a snapshot . therefore any modification you make to the returned list will be present inside the jaxb object . this is why there is not a set method for the position property . for example , to add a new item , do as follows : getposition . add newitem ; objects of the following type s are allowed in the list double concode_field_sep double mass concode_elem_sep List<Double> position concode_elem_sep List<Double> velocity concode_field_sep List<Double> getVelocity concode_elem_sep double getMass concode_elem_sep void setMass
target: List < Double > function ( ) { if ( position == null ) { position = new ArrayList < Double > ( ) ; } return this . position ; }