code: public MapView setZoom(final double zoom) {
          final double rounded = Math.round(zoom);
          if (rounded < MIN_ZOOM || rounded > MAX_ZOOM) {
              return this;
          }
          this.zoom.set(rounded);
          return this;
      }
docs: sets the zoom level. the zoom value is rounded to the next whole number using {@link Math#round(double)} and then
  checked to be in the range between {@link #MIN_ZOOM} and {@link #MAX_ZOOM }. If the value is not in this range,
  the call is ignored.
  
  @param zoom
  new zoom level
  @return this object