public static Percentage fromString(final String str) {
    checkArgument(str != null);
    return fromInt(parseInt(str));
  }
Parse a string representing a percentage.

@param str A string representing a valid percentage between 0 and 100 inclusive.
@return The percentage.
@throws IllegalArgumentException if the provided string is {@code null}.
@throws IllegalArgumentException if the string is either not a number, or not a percentage
util/src/main/java/org/hyperledger/besu/util/number/Percentage.java