Program: 2075
Project: 2075
Buggy source:
public void onEnable(){
  BasicExecutor executor=new BasicExecutor(this);
  this.getCommand("String_Node_Str").setExecutor(executor);
  this.getCommand("String_Node_Str").setExecutor(executor);
  TraderExecutor traderExecutor=new TraderExecutor(this);
  this.getCommand("String_Node_Str").setExecutor(traderExecutor);
  TogglerExecutor togglerExecutor=new TogglerExecutor(this);
  this.getCommand("String_Node_Str").setExecutor(togglerExecutor);
  PluginManager pm=getServer().getPluginManager();
  pm.registerEvent(Event.Type.ENTITY_DAMAGE,l,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.ENTITY_TARGET,l,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.CUSTOM_EVENT,cl,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.CHUNK_LOAD,wl,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.CHUNK_UNLOAD,wl,Event.Priority.Normal,this);
  getServer().getPluginManager().registerEvent(Event.Type.PLUGIN_ENABLE,pl,Event.Priority.Monitor,this);
  PluginDescriptionFile pdfFile=this.getDescription();
  Permission.initialize(getServer());
  setupVariables();
  if (getServer().getScheduler().scheduleSyncDelayedTask(this,new Runnable(){
    @Override public void run(){
      setupNPCs();
    }
  }
) == -1) {
    log.info("String_Node_Str");
    setupNPCs();
  }
  setupHelp();
  getServer().getScheduler().scheduleSyncRepeatingTask(this,new TickTask(this,npcRange),tickDelay,tickDelay);
  getServer().getScheduler().scheduleSyncRepeatingTask(this,new Runnable(){
    @Override public void run(){
      log.info("String_Node_Str");
      PropertyPool.saveAll();
      TraderPropertyPool.saveAll();
      log.info("String_Node_Str");
    }
  }
,saveDelay,saveDelay);
  log.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str"+ pdfFile.getVersion()+ "String_Node_Str"+ codename+ "String_Node_Str");
}

Fixed version (ground truth):
public void onEnable(){
  File file=new File("String_Node_Str");
  file.delete();
  file=new File("String_Node_Str");
  file.delete();
  BasicExecutor executor=new BasicExecutor(this);
  this.getCommand("String_Node_Str").setExecutor(executor);
  this.getCommand("String_Node_Str").setExecutor(executor);
  TraderExecutor traderExecutor=new TraderExecutor(this);
  this.getCommand("String_Node_Str").setExecutor(traderExecutor);
  TogglerExecutor togglerExecutor=new TogglerExecutor(this);
  this.getCommand("String_Node_Str").setExecutor(togglerExecutor);
  PluginManager pm=getServer().getPluginManager();
  pm.registerEvent(Event.Type.ENTITY_DAMAGE,l,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.ENTITY_TARGET,l,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.CUSTOM_EVENT,cl,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.CHUNK_LOAD,wl,Event.Priority.Normal,this);
  pm.registerEvent(Event.Type.CHUNK_UNLOAD,wl,Event.Priority.Normal,this);
  getServer().getPluginManager().registerEvent(Event.Type.PLUGIN_ENABLE,pl,Event.Priority.Monitor,this);
  PluginDescriptionFile pdfFile=this.getDescription();
  Permission.initialize(getServer());
  setupVariables();
  if (getServer().getScheduler().scheduleSyncDelayedTask(this,new Runnable(){
    @Override public void run(){
      setupNPCs();
    }
  }
) == -1) {
    log.info("String_Node_Str");
    setupNPCs();
  }
  setupHelp();
  getServer().getScheduler().scheduleSyncRepeatingTask(this,new TickTask(this,npcRange),tickDelay,tickDelay);
  getServer().getScheduler().scheduleSyncRepeatingTask(this,new Runnable(){
    @Override public void run(){
      log.info("String_Node_Str");
      PropertyPool.saveAll();
      TraderPropertyPool.saveAll();
      log.info("String_Node_Str");
    }
  }
,saveDelay,saveDelay);
  log.info("String_Node_Str" + pdfFile.getName() + "String_Node_Str"+ pdfFile.getVersion()+ "String_Node_Str"+ codename+ "String_Node_Str");
}