def license(val = NULL)
      if null?(val)
        @license || project.license
      else
        unless val.is_a?(String)
          raise InvalidValue.new(:license, "be a String")
        end

        @license = val
      end
    end
def license(val = NULL)
      if null?(val)
        @license || project.license
      else
        unless val.is_a?(String)
          raise InvalidValue.new(:license, "be a String")
        end

        @license = val
      end
    end
Set or return the license for this package.

 @example
   license "Apache 2.0"

 @param [String] val
   the license for this package

 @return [String]
   the license for this package