code: public void setServerCustomizers(
  			Collection<? extends ServerRSocketFactoryCustomizer> serverCustomizers) {
  		Assert.notNull(serverCustomizers, "ServerCustomizers must not be null");
  		this.serverCustomizers = new ArrayList<>(serverCustomizers);
  	}
docs: Set {@link ServerRSocketFactoryCustomizer}s that should be applied to the RSocket
  server builder. Calling this method will replace any existing customizers.
  @param serverCustomizers the customizers to set