public void addEntry(QuadTreeEntry entry) {       
    	if (m_head == null) {                    
            m_head = entry;
            m_tail = entry;            
            //late clean of next references
            entry.setNext(null);
    	} else if (entry != m_head && entry != m_tail && entry.getNext() == null) {
            entry.setNext(m_head);
            m_head = entry;
        } else {
            // Entry already exists in the node. Adding the same object will cause
            // loops when traversing the list.
            if (LOG.isError()) {
                LOG.error("QuadTreeNode.addEntry()", "Object already exists in the node!");
            }
            return;
        }
        m_HasBeenChanged = true;
        m_size++;
        iHasEntrysAdded = true;
    }