}
        },
        "creation_date" : "1509021051038",
        "number_of_shards" : "5",
        "number_of_replicas" : "1",
        "uuid" : "H4zzbuU5SJWFOLRnofoiNw",
        "version" : {
          "created" : "6000051"
        },
        "provided_name" : "fess_config.data_config"
      }
    }
  }

      "index" : {
        "creation_date" : "1509021058796",
        "number_of_shards" : "5",
        "number_of_replicas" : "1",
        "uuid" : "5EWS2-qMT2WwHG0yPrhP3Q",
        "version" : {
          "created" : "6000051"
        },
        "provided_name" : "fess_user.group"
      }
    }
  }

     */
    private final int lineNumber;

    /**
     * The one-based index of the column containing the error.
     */
    private final int columnNumber;

    /**
     * Creates a new parser exception with the specified details.
     *
     * @param message The error message, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.

     */
    private final int lineNumber;

    /**
     * The one-based index of the column containing the error.
     */
    private final int columnNumber;

    /**
     * Creates a new parser exception with the specified details.
     *
     * @param message The error message, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.

   * the result is chosen uniformly at random in [0, numBits), and then the result is chosen in that
   * range uniformly at random. Zero is treated as having log2 == 0.
   */
  static BigInteger randomNonNegativeBigInteger(int numBits) {
    int digits = RANDOM_SOURCE.nextInt(numBits);
    if (digits == 0) {
      return new BigInteger(1, RANDOM_SOURCE);
    } else {

      "index" : {
        "creation_date" : "1509021060038",
        "number_of_shards" : "5",
        "number_of_replicas" : "1",
        "uuid" : "LRohRohXTCGxGdsabXPNnQ",
        "version" : {
          "created" : "6000051"
        },
        "provided_name" : "fess_log.favorite_log"
      }
    }
  }

      "index" : {
        "creation_date" : "1509021049746",
        "number_of_shards" : "5",
        "number_of_replicas" : "1",
        "uuid" : "0xToIxg0R1KjZqA0ynv9PQ",
        "version" : {
          "created" : "6000051"
        },
        "provided_name" : "fess_config.bad_word"
      }
    }
  }

      "index" : {
        "creation_date" : "1509021056434",
        "number_of_shards" : "5",
        "number_of_replicas" : "1",
        "uuid" : "Zrp1Be7PS1ySzKAjlrpICg",
        "version" : {
          "created" : "6000051"
        },
        "provided_name" : "fess_config.request_header"
      }
    }
  }

   */
  public double populationCovariance() {
    checkState(count() != 0);
    return sumOfProductsOfDeltas / count();
  }

  /**
   * Returns the sample covariance of the values. The count must be greater than one.
   *
   * <p>This is not guaranteed to return zero when the dataset consists of the same pair of values
   * multiple times, due to numerical errors.
   *
   * <h3>Non-finite values</h3>
   *

      "index" : {
        "creation_date" : "1509021053135",
        "number_of_shards" : "5",
        "number_of_replicas" : "1",
        "uuid" : "-gono3d2R0KP5po-ggBr0A",
        "version" : {
          "created" : "6000051"
        },
        "provided_name" : "fess_config.file_authentication"
      }
    }
  }