code: public Optional<AddOnInformation> getAddOnInformation(final int serverID) {
          if (serverID == -1) {
              return Optional.empty();
          }
  
          return addOnInformations.stream()
                  .filter(addOn -> addOn.getServerID().orElse(-1) == serverID)
                  .findFirst();
      }
docs: Gets the {@link AddOnInformation} that has the given id. The id is the serverID of the addOn.
  
  @param serverID The id is the serverID of the addOn.
  @return An optional wrapping the addOn. If the addOn was found the optional will not be empty and otherwise it
  will.