You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: idle.go
    path of file: ./repos/zeebe/clients/go/vendor/google.golang.org/grpc/internal/idle
    
    the code of the file until where you have to start completion: /*
 *
 * Copyright 2023 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may
    
func (m *Manager) OnCallEnd() {
	if m.isClosed() {
		return
	}

	// Record the time at which the most recent call finished.
	atomic.StoreInt64(&m.lastCallEndTime, time.Now().UnixNano())

	// Decrement the active calls count. This count can temporarily go negative
	// when the timer callback is in the process of moving the channel to idle
	// mode, but one or more RPCs come in and complete before the timer callback
	// can get done with the process of moving to idle mode.
	atomic.AddInt32(&m.activeCallsCount, -1)
}