code: public static Attribute<Void> attr( String attribute, String value )
      {
          return new Attribute<Void>()
          {
              @Override
              public String name()
              {
                  return attribute;
              }
  
              @Override
              public String value( Void target )
              {
                  return value;
              }
          };
      }
docs: Generate html tag attributes for use in {@link}.
  
  This is an alternative to {@code body.tag( "img", src -> imgUri )}, allowing the use of the API on earlier
  builds of the JDK as {@code body.tag( "img", attr( "src", imgUri ) )}.
  
  @param attribute the name of the attribute.
  @param value     the value of the attribute.
  @return an object that generates the attribute.