code: public String getUnicode(Fitzpatrick fitzpatrick) {
      if (!this.supportsFitzpatrick()) {
        throw new UnsupportedOperationException(
          "Cannot get the unicode with a fitzpatrick modifier, " +
          "the emoji doesn't support fitzpatrick."
        );
      } else if (fitzpatrick == null) {
        return this.getUnicode();
      }
      return this.getUnicode() + fitzpatrick.unicode;
    }
docs: Returns the unicode representation of the emoji associated with the
  provided Fitzpatrick modifier.<br>
  If the modifier is null, then the result is similar to
  {@link Emoji#getUnicode()}
  
  @param fitzpatrick the fitzpatrick modifier or null
  
  @return the unicode representation
  @throws UnsupportedOperationException if the emoji doesn't support the
  Fitzpatrick modifiers