code: List<AddOnInstallationStatusListener> getAddOnInstallationStatusListeners() {
          if (addOnInstallationStatusListeners == null) {
              return Collections.emptyList();
          }
          return Collections.unmodifiableList(addOnInstallationStatusListeners);
      }
docs: Gets the {@link AddOnInstallationStatusListener}s added to this hook.
  
  @return an unmodifiable {@code List} containing the added {@code AddOnInstallationStatusListener}s, never {@code null}.
  @since 2.5.0