public TextSearchRequest radius(int radius) {
    if (radius > 50000) {
      throw new IllegalArgumentException("The maximum allowed radius is 50,000 meters.");
    }
    return param("radius", String.valueOf(radius));
  }
Specifies the distance (in meters) within which to bias place results.

@param radius The radius of the search bias.
@return Returns this {@code TextSearchRequest} for call chaining.
src/main/java/com/google/maps/TextSearchRequest.java