question: public StaticMap visible ( GeoPoint ... geoPoints ) { visible . addAll ( Arrays . asList ( geoPoints ) ) ; return this ; }
target:  Images may specify a viewport by adding visible locations. The visible parameter instructs the Google Static Maps API service to construct a map such that the specified locations remain visible (this parameter may be combined with existing markers or paths to define a visible region as well). Defining a viewport in this manner obviates the need to specify an exact zoom level.