Program: 10596
Project: 10596
Buggy source:
@Override public boolean onBlockActivated(World world,BlockPos pos,IBlockState state,EntityPlayer player,EnumHand hand,EnumFacing side,float hitX,float hitY,float hitZ){
  ItemStack item=player.getHeldItem(hand);
  if (hand == EnumHand.OFF_HAND)   return false;
  if (world.isRemote && Minecraft.getSystemTime() == ignoreEventTime) {
    ignoreEventTime=0;
    return false;
  }
  TileEntityDrawers tileDrawers=getTileEntitySafe(world,pos);
  if (!SecurityManager.hasAccess(player.getGameProfile(),tileDrawers))   return false;
  if (StorageDrawers.config.cache.debugTrace) {
    FMLLog.log(StorageDrawers.MOD_ID,Level.INFO,"String_Node_Str");
    FMLLog.log(StorageDrawers.MOD_ID,Level.INFO,(item.isEmpty()) ? "String_Node_Str" : "String_Node_Str" + item.toString());
  }
  if (!item.isEmpty()) {
    if (item.getItem() instanceof ItemTrim && player.isSneaking()) {
      if (!retrimBlock(world,pos,item))       return false;
      if (!player.capabilities.isCreativeMode) {
        item.shrink(1);
        if (item.getCount() <= 0)         player.inventory.setInventorySlotContents(player.inventory.currentItem,ItemStack.EMPTY);
      }
      return true;
    }
 else     if (item.getItem() instanceof ItemUpgrade) {
      if (item.getItem() == ModItems.upgradeOneStack && !tileDrawers.canAddOneStackUpgrade()) {
        if (!world.isRemote)         player.sendStatusMessage(new TextComponentTranslation("String_Node_Str"));
        return false;
      }
      if (!tileDrawers.canAddUpgrade(item))       return false;
      if (!tileDrawers.addUpgrade(item)) {
        if (!world.isRemote)         player.sendStatusMessage(new TextComponentTranslation("String_Node_Str"),true);
        return false;
      }
      world.notifyBlockUpdate(pos,state,state,3);
      if (!player.capabilities.isCreativeMode) {
        item.shrink(1);
        if (item.getCount() <= 0)         player.inventory.setInventorySlotContents(player.inventory.currentItem,ItemStack.EMPTY);
      }
      return true;
    }
 else     if (item.getItem() == ModItems.drawerKey) {
      boolean locked=tileDrawers.isItemLocked(LockAttribute.LOCK_POPULATED);
      tileDrawers.setItemLocked(LockAttribute.LOCK_POPULATED,!locked);
      tileDrawers.setItemLocked(LockAttribute.LOCK_EMPTY,!locked);
      return true;
    }
 else     if (item.getItem() == ModItems.shroudKey) {
      tileDrawers.setIsShrouded(!tileDrawers.isShrouded());
      return true;
    }
 else     if (item.getItem() == ModItems.quantifyKey) {
      tileDrawers.setIsShowingQuantity(!tileDrawers.isShowingQuantity());
      return true;
    }
 else     if (item.getItem() instanceof ItemPersonalKey) {
      String securityKey=((ItemPersonalKey)item.getItem()).getSecurityProviderKey(item.getItemDamage());
      ISecurityProvider provider=StorageDrawers.securityRegistry.getProvider(securityKey);
      if (tileDrawers.getOwner() == null) {
        tileDrawers.setOwner(player.getPersistentID());
        tileDrawers.setSecurityProvider(provider);
      }
 else       if (SecurityManager.hasOwnership(player.getGameProfile(),tileDrawers)) {
        tileDrawers.setOwner(null);
        tileDrawers.setSecurityProvider(null);
      }
 else       return false;
      return true;
    }
 else     if (item.getItem() == ModItems.tape)     return false;
  }
 else   if (item.isEmpty() && player.isSneaking()) {
    if (tileDrawers.isSealed()) {
      tileDrawers.setIsSealed(false);
      return true;
    }
 else     if (StorageDrawers.config.cache.enableDrawerUI) {
      player.openGui(StorageDrawers.instance,GuiHandler.drawersGuiID,world,pos.getX(),pos.getY(),pos.getZ());
      return true;
    }
  }
  if (tileDrawers.getDirection() != side.ordinal())   return false;
  if (tileDrawers.isSealed())   return false;
  int slot=getDrawerSlot(getDrawerCount(state),side.ordinal(),hitX,hitY,hitZ);
  tileDrawers.interactPutItemsIntoSlot(slot,player);
  if (item.isEmpty())   player.setHeldItem(hand,ItemStack.EMPTY);
  return true;
}

Fixed version (ground truth):
@Override public boolean onBlockActivated(World world,BlockPos pos,IBlockState state,EntityPlayer player,EnumHand hand,EnumFacing side,float hitX,float hitY,float hitZ){
  ItemStack item=player.getHeldItem(hand);
  if (hand == EnumHand.OFF_HAND)   return false;
  if (world.isRemote && Minecraft.getSystemTime() == ignoreEventTime) {
    ignoreEventTime=0;
    return false;
  }
  TileEntityDrawers tileDrawers=getTileEntitySafe(world,pos);
  if (!SecurityManager.hasAccess(player.getGameProfile(),tileDrawers))   return false;
  if (StorageDrawers.config.cache.debugTrace) {
    FMLLog.log(StorageDrawers.MOD_ID,Level.INFO,"String_Node_Str");
    FMLLog.log(StorageDrawers.MOD_ID,Level.INFO,(item.isEmpty()) ? "String_Node_Str" : "String_Node_Str" + item.toString());
  }
  if (!item.isEmpty()) {
    if (item.getItem() instanceof ItemTrim && player.isSneaking()) {
      if (!retrimBlock(world,pos,item))       return false;
      if (!player.capabilities.isCreativeMode) {
        item.shrink(1);
        if (item.getCount() <= 0)         player.inventory.setInventorySlotContents(player.inventory.currentItem,ItemStack.EMPTY);
      }
      return true;
    }
 else     if (item.getItem() instanceof ItemUpgrade) {
      if (item.getItem() == ModItems.upgradeOneStack && !tileDrawers.canAddOneStackUpgrade()) {
        if (!world.isRemote)         player.sendStatusMessage(new TextComponentTranslation("String_Node_Str"),true);
        return false;
      }
      if (!tileDrawers.canAddUpgrade(item))       return false;
      if (!tileDrawers.addUpgrade(item)) {
        if (!world.isRemote)         player.sendStatusMessage(new TextComponentTranslation("String_Node_Str"),true);
        return false;
      }
      world.notifyBlockUpdate(pos,state,state,3);
      if (!player.capabilities.isCreativeMode) {
        item.shrink(1);
        if (item.getCount() <= 0)         player.inventory.setInventorySlotContents(player.inventory.currentItem,ItemStack.EMPTY);
      }
      return true;
    }
 else     if (item.getItem() == ModItems.drawerKey) {
      boolean locked=tileDrawers.isItemLocked(LockAttribute.LOCK_POPULATED);
      tileDrawers.setItemLocked(LockAttribute.LOCK_POPULATED,!locked);
      tileDrawers.setItemLocked(LockAttribute.LOCK_EMPTY,!locked);
      return true;
    }
 else     if (item.getItem() == ModItems.shroudKey) {
      tileDrawers.setIsShrouded(!tileDrawers.isShrouded());
      return true;
    }
 else     if (item.getItem() == ModItems.quantifyKey) {
      tileDrawers.setIsShowingQuantity(!tileDrawers.isShowingQuantity());
      return true;
    }
 else     if (item.getItem() instanceof ItemPersonalKey) {
      String securityKey=((ItemPersonalKey)item.getItem()).getSecurityProviderKey(item.getItemDamage());
      ISecurityProvider provider=StorageDrawers.securityRegistry.getProvider(securityKey);
      if (tileDrawers.getOwner() == null) {
        tileDrawers.setOwner(player.getPersistentID());
        tileDrawers.setSecurityProvider(provider);
      }
 else       if (SecurityManager.hasOwnership(player.getGameProfile(),tileDrawers)) {
        tileDrawers.setOwner(null);
        tileDrawers.setSecurityProvider(null);
      }
 else       return false;
      return true;
    }
 else     if (item.getItem() == ModItems.tape)     return false;
  }
 else   if (item.isEmpty() && player.isSneaking()) {
    if (tileDrawers.isSealed()) {
      tileDrawers.setIsSealed(false);
      return true;
    }
 else     if (StorageDrawers.config.cache.enableDrawerUI) {
      player.openGui(StorageDrawers.instance,GuiHandler.drawersGuiID,world,pos.getX(),pos.getY(),pos.getZ());
      return true;
    }
  }
  if (tileDrawers.getDirection() != side.ordinal())   return false;
  if (tileDrawers.isSealed())   return false;
  int slot=getDrawerSlot(getDrawerCount(state),side.ordinal(),hitX,hitY,hitZ);
  tileDrawers.interactPutItemsIntoSlot(slot,player);
  if (item.isEmpty())   player.setHeldItem(hand,ItemStack.EMPTY);
  return true;
}