How to deal with ConcurrentModificationException exception?

I’m getting this error, when I’m working with dropdown in table.

I’m using bellow code:

this.SetDropDownValueByRowNamberAndColumnName = function(rowNumber, columnName, dropDownValue){
    WaitObject(obj,Project.Variables.timeOut);
    obj.ClickCell(rowNumber, columnName);
    aqUtils.Delay(2000);
    Aliases.bla-bla.DropDownItem.ClickItem(dropDownValue);  
  }

At first I thought that I need increase Delay(it was 100 ms), but no it does not work. Also I was trying to record the script and got the same error.

So what can cause this error?

P.S. Sometimes it works fine.

I would be grateful for any help.

Thanks in advance

Denis

Error code:

Exception in thread "AWT-EventQueue-2" java.util.ConcurrentModificationException
	at java.util.HashMap$Ha**bleep**erator.nextNode(Unknown Source)
	at java.util.HashMap$KeyIterator.next(Unknown Source)
	at com.intransit.dbs.swing.mvtable.DefaultMVEditor.fireCellEditingStopped(DefaultMVEditor.java:664)
	at com.intransit.dbs.swing.mvtable.DefaultMVEditor.stopCellEditing(DefaultMVEditor.java:578)
	at com.intransit.dbs.swing.DBSMVTable.stopCellEditing(DBSMVTable.java:1508)
	at com.intransit.dbs.swing.DBSMVTable$CellEditorFocusListener.focusLost(DBSMVTable.java:2019)
	at java.awt.AWTEventMulticaster.focusLost(Unknown Source)
	at java.awt.Component.processFocusEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)