public static PositiveNumber fromString(final String str) {
    checkArgument(str != null);
    PositiveNumber positiveNumber = new PositiveNumber(parseInt(str));
    checkArgument(positiveNumber.getValue() > 0);
    return positiveNumber;
  }
Parse a string representing a positive number.

@param str A string representing a valid positive number strictly greater than 0.
@return The parsed int.
@throws IllegalArgumentException if the provided string is {@code null}.
@throws IllegalArgumentException if the string is either not a number, or not a positive number
util/src/main/java/org/hyperledger/besu/util/number/PositiveNumber.java