[Eclipse] Diagram modifications removes data in XML file

Hello,

I'am using Eclipse to create my Workflow. If I change something in the diagram (ie : just move the endEvent) and save. All code inside <activiti:string> is deleted.

Please look at the "<activiti:string>execution.setVariable('sgfwf_approveRejectOutcome',task.getVariable('sgfwf_approveRejectOutcome'));</activiti:string>"

xml file before a change in diagram
Code:
<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:activiti="http://activiti.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://activiti.org/bpmn20">
<process id="Simple" name="Adhoc Activiti Process 08:33">
<startEvent id="start" name="Start" activiti:formKey="sgfwf:submitStart"></startEvent>
<userTask id="modifyReview" name="Add/Modify Data, Accept or Reject" activiti:assignee="$

{bpm_assignee.properties.userName}" activiti:formKey="sgfwf:modifyReviewTask">
<extensionElements>
<activiti:taskListener event="complete" class="org.alfresco.repo.workflow.activiti.tasklistener.ScriptTaskListener">
<activiti:field name="script">
<activiti:string>execution.setVariable('sgfwf_approveRejectOutcome',task.getVariable('sgfwf_approveRejectOutcome'));</activiti:string>
</activiti:field>


xml file after a change in diagram
Code:
<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:activiti="http://activiti.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://activiti.org/bpmn20">
<process id="MyProcess" name="Adhoc Activiti Process 08:33">
<startEvent id="start" name="Start" activiti:formKey="sgfwf:submitStart"></startEvent>
<userTask id="modifyReview" name="Add/Modify Data, Accept or Reject" activiti:assignee="${bpm_assignee.properties.userName}

" activiti:formKey="sgfwf:modifyReviewTask">
<extensionElements>
<activiti:taskListener event="complete" class="org.alfresco.repo.workflow.activiti.tasklistener.ScriptTaskListener">
<activiti:field name="script">
<activiti:string></activiti:string>
</activiti:field>

Thank you