code: public static void setIsImplicit(ArgumentUnit argumentUnit, boolean implicit)
              throws IllegalArgumentException
      {
          int length = argumentUnit.getEnd() - argumentUnit.getBegin();
  
          if (length > 0) {
              throw new IllegalArgumentException("Cannot set 'implicit' property to component " +
                      "with non-zero length (" + length + ")");
          }
  
          ArgumentUnitUtils.setProperty(argumentUnit, ArgumentUnitUtils.PROP_KEY_IS_IMPLICIT,
                  Boolean.valueOf(implicit).toString());
      }
docs: Sets the implicit value to the argument
  
  @param argumentUnit argument unit
  @param implicit     boolean value
  @throws java.lang.IllegalArgumentException if the length of argument is non-zero