question: gets the value of the sizes 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 sizes property . for example , to add a new item , do as follows : getsizes . add newitem ; objects of the following type s are allowed in the list size concode_field_sep Double manualCreativeRotationWeight concode_elem_sep Long creativeSetId concode_elem_sep StartDateTimeType startDateTimeType concode_elem_sep DateTime lastModifiedDateTime concode_elem_sep Long lineItemId concode_elem_sep String destinationUrl concode_elem_sep DateTime endDateTime concode_elem_sep Long creativeId concode_elem_sep DateTime startDateTime concode_elem_sep Integer sequentialCreativeRotationIndex concode_elem_sep List<Size> sizes concode_elem_sep LineItemCreativeAssociationStats stats concode_elem_sep LineItemCreativeAssociationStatus status concode_field_sep void setManualCreativeRotationWeight concode_elem_sep LineItemCreativeAssociationStats getStats concode_elem_sep void setEndDateTime concode_elem_sep void setLastModifiedDateTime concode_elem_sep Long getCreativeId concode_elem_sep Double getManualCreativeRotationWeight concode_elem_sep void setCreativeId concode_elem_sep void setLineItemId concode_elem_sep StartDateTimeType getStartDateTimeType concode_elem_sep DateTime getStartDateTime concode_elem_sep void setStartDateTimeType concode_elem_sep Integer getSequentialCreativeRotationIndex concode_elem_sep void setStats concode_elem_sep LineItemCreativeAssociationStatus getStatus concode_elem_sep void setStatus concode_elem_sep void setCreativeSetId concode_elem_sep Long getLineItemId concode_elem_sep DateTime getEndDateTime concode_elem_sep Long getCreativeSetId concode_elem_sep String getDestinationUrl concode_elem_sep DateTime getLastModifiedDateTime concode_elem_sep void setDestinationUrl concode_elem_sep void setSequentialCreativeRotationIndex concode_elem_sep void setStartDateTime
target: List < Size > function ( ) { if ( sizes == null ) { sizes = new ArrayList < Size > ( ) ; } return this . sizes ; }