implemented review suggestion

Author: edoardocomar

core/src/main/scala/kafka/network/SocketServer.scala

@@ -98,8 +98,7 @@ class SocketServer(
   private val memoryPoolDepletedPercentMetricName = metrics.metricName("MemoryPoolAvgDepletedPercent", JSocketServer.METRICS_GROUP)
   private val memoryPoolDepletedTimeMetricName = metrics.metricName("MemoryPoolDepletedTimeTotal", JSocketServer.METRICS_GROUP)
   memoryPoolSensor.add(new Meter(TimeUnit.MILLISECONDS, memoryPoolDepletedPercentMetricName, memoryPoolDepletedTimeMetricName))
-  // accessible for testing
-  val memoryPool = if (config.queuedMaxBytes > 0) new SimpleMemoryPool(config.queuedMaxBytes, config.socketRequestMaxBytes, false, memoryPoolSensor) else MemoryPool.NONE
+  private[network] val memoryPool = if (config.queuedMaxBytes > 0) new SimpleMemoryPool(config.queuedMaxBytes, config.socketRequestMaxBytes, false, memoryPoolSensor) else MemoryPool.NONE
   // data-plane
   private[network] val dataPlaneAcceptors = new ConcurrentHashMap[Endpoint, DataPlaneAcceptor]()
   val dataPlaneRequestChannel = new RequestChannel(maxQueuedRequests, time, apiVersionManager.newRequestMetrics)