code: public void addApiImplementor(ApiImplementor apiImplementor) {
          if (apiImplementor == null) {
              throw new IllegalArgumentException("Parameter apiImplementor must not be null.");
          }
  
          if (apiImplementors == null) {
              apiImplementors = new ArrayList<>();
          }
          apiImplementors.add(apiImplementor);
      }
docs: Adds the given {@code apiImplementor} to the extension hook, to be later added to the
  {@link org.zaproxy.zap.extension.api.API API}.
  <p>
  By default, the {@code ApiImplementor}s added to this extension hook are removed from the {@code API} when the extension
  is unloaded.
  
  @param apiImplementor the ApiImplementor that will be added to the ZAP API
  @throws IllegalArgumentException if the given {@code apiImplementor} is {@code null}.
  @since 2.6.0