question: gets the value of the urls 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 urls property . for example , to add a new item , do as follows : geturls . add newitem ; objects of the following type s are allowed in the list mediasizestringmapentry concode_field_sep String sourceUrl concode_elem_sep List<MediaSizeStringMapEntry> urls concode_elem_sep String creationTime concode_elem_sep Long fileSize concode_elem_sep String name concode_elem_sep String mediaType concode_elem_sep MediaMimeType mimeType concode_elem_sep Long mediaId concode_elem_sep MediaMediaType type concode_elem_sep Long referenceId concode_elem_sep List<MediaSizeDimensionsMapEntry> dimensions concode_field_sep void setReferenceId concode_elem_sep void setName concode_elem_sep String getName concode_elem_sep MediaMimeType getMimeType concode_elem_sep void setFileSize concode_elem_sep void setMimeType concode_elem_sep Long getMediaId concode_elem_sep void setCreationTime concode_elem_sep String getMediaType concode_elem_sep void setMediaType concode_elem_sep void setMediaId concode_elem_sep void setType concode_elem_sep Long getReferenceId concode_elem_sep String getSourceUrl concode_elem_sep List<MediaSizeDimensionsMapEntry> getDimensions concode_elem_sep Long getFileSize concode_elem_sep MediaMediaType getType concode_elem_sep void setSourceUrl concode_elem_sep String getCreationTime
target: List < MediaSizeStringMapEntry > function ( ) { if ( urls == null ) { urls = new ArrayList < MediaSizeStringMapEntry > ( ) ; } return this . urls ; }