def require_marc4j_jar(jardir)
      unless defined? JRUBY_VERSION
        raise LoadError.new, "MARC::MARC4J requires the use of JRuby", nil
      end
      if jardir
        Dir.glob("#{jardir}/*.jar") do |x|
          require x
        end
      else
        Dir.glob(File.join(DEFAULT_JAR_RELATIVE_DIR, "*.jar")) do |x|
          require x
        end
      end
    end
def require_marc4j_jar(jardir)
      unless defined? JRUBY_VERSION
        raise LoadError.new, "MARC::MARC4J requires the use of JRuby", nil
      end
      if jardir
        Dir.glob("#{jardir}/*.jar") do |x|
          require x
        end
      else
        Dir.glob(File.join(DEFAULT_JAR_RELATIVE_DIR, "*.jar")) do |x|
          require x
        end
      end
    end
Try to get the specified jarfile, or the bundled one if nothing is specified