Revert "ServerSocketAppenderBase now uses ExecutorService from context"

This reverts commit 6497104.

Author: ceharris

logback-core/src/main/java/ch/qos/logback/core/net/server/ServerSocketAppenderBase.java

@@ -63,7 +63,7 @@ public void start() {
       ServerSocket socket = getServerSocketFactory().createServerSocket(
           getPort(), getBacklog(), getInetAddress());    
       ServerListener<RemoteLoggerClient> listener = createServerListener(socket);
-      executor = createExecutor();
+      executor = getThreadPool().createExecutor();
       runner = createServerRunner(listener, executor);
       runner.setContext(getContext());
       runner.start();
@@ -86,24 +86,12 @@ protected ServerRunner<RemoteLoggerClient> createServerRunner(
         getClientQueueSize());
   }
 
-  protected ExecutorService createExecutor() {
-    if (getThreadPool() == null) {
-      return getContext().getExecutorService();
-    }
-    return getThreadPool().createExecutor();
-  }
-  
   @Override
   public void stop() {
     if (!isStarted()) return;
     try {
       runner.stop();
-      
-      // shutdown the executor only if we created our own
-      if (executor != getContext().getExecutorService()) {
-        executor.shutdownNow();
-      }
-      
+      executor.shutdownNow();
       super.stop();
     }
     catch (IOException ex) {
@@ -242,10 +230,13 @@ public void setClientQueueSize(int clientQueueSize) {
 
   /**
    * Gets the server's thread pool configuration.
-   * @return thread pool configuration or {@code null} if no configuration was
-   *    provided
+   * @return thread pool configuration; if no thread pool configuration was
+   *    provided, a default configuration is returned
    */
   public ThreadPoolFactoryBean getThreadPool() {
+    if (threadPool == null) {
+      return new ThreadPoolFactoryBean();
+    }
     return threadPool;
   }