code: public Minutes plus(int minutes) {
          if (minutes == 0) {
              return this;
          }
          return Minutes.minutes(FieldUtils.safeAdd(getValue(), minutes));
      }
docs: Returns a new instance with the specified number of minutes added.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param minutes  the amount of minutes to add, may be negative
  @return the new period plus the specified number of minutes
  @throws ArithmeticException if the result overflows an int