code: @Nonnull
    public void setRegistry (@Nonnull final IAjaxRegistry aRegistry)
    {
      ValueEnforcer.notNull (aRegistry, "Registry");
      if (m_aRWLock.readLocked ( () -> m_aRegistry.getAllRegisteredFunctions ().isNotEmpty ()))
        throw new IllegalStateException ("Cannot change the registry after a function was already registered!");
  
      m_aRWLock.writeLocked ( () -> m_aRegistry = aRegistry);
    }
docs: Set the global registry to be used. Note: this API can only called BEFORE
  registrations are performed. Afterwards an {@link IllegalStateException} is
  thrown if this API is invoked.
  
  @param aRegistry
  The registry to use. May not be <code>null</code>.