anchor.diff:            "dfs.nameservices" = "namenode1";
           }
         '';
  -      description = "Hadoop hdfs-site.xml definition";
  +      description = ''
  +        Hadoop hdfs-site.xml definition
  +        <link xlink:href="https://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/hdfs-default.xml"/>
  +      '';
       };
   
       mapredSite = mkOption {
  
positive.code:           "mapreduce.map.java.opts" = "-Xmx900m -XX:+UseParallelGC";
          }
        '';
        description = "Hadoop mapred-site.xml definition";
      };
  
      yarnSite = mkOption {
  
negative.code:           "hadoop.http.max.threads" = 500;
          }
        '';
        description = ''
          Hadoop httpfs-site.xml definition
          <link xlink:href="https://hadoop.apache.org/docs/current/hadoop-hdfs-httpfs/httpfs-default.html"/>
        '';
      };
  
      log4jProperties = mkOption {
  