When accessing to CMS by two browsers in same time, SAXClientSideElementHelper sometimes is responsible of a ConcurrentModificationExcepetion, or a NullPointerException or a OutOfMemoryError

• NPE

  Caused by: java.lang.NullPointerException
  	at org.apache.cocoon.xml.XMLUtils.data(XMLUtils.java:324)
  	at org.apache.cocoon.xml.XMLUtils.createElement(XMLUtils.java:481)
  	at org.ametys.runtime.ui.SAXClientSideElementHelper.saxDefinition(SAXClientSideElementHelper.java:104)
  	at org.ametys.cms.workspace.ribbon.RibbonConfigurationManager.saxRibbonDefinition(RibbonConfigurationManager.java:354)
  	at org.ametys.cms.workspace.WorkspaceGenerator.doGenerate(WorkspaceGenerator.java:117)
  	at org.ametys.web.workspace.WorkspaceGenerator.generate(WorkspaceGenerator.java:91)
  

• ConcurrentModificationException

  Caused by: java.util.ConcurrentModificationException
  	at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
  	at java.util.HashMap$KeyIterator.next(HashMap.java:827)
  	at org.ametys.runtime.ui.SAXClientSideElementHelper.saxDefinition(SAXClientSideElementHelper.java:79)
  	at org.ametys.cms.workspace.uitool.UIToolsConfigurationManager.saxDefaultState(UIToolsConfigurationManager.java:180)
  	at org.ametys.cms.workspace.WorkspaceGenerator.doGenerate(WorkspaceGenerator.java:120)
  	at org.ametys.web.workspace.WorkspaceGenerator.generate(WorkspaceGenerator.java:91)
  	at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline.processXMLPipeline(AbstractProcessingPipeline.java:579)
  	... 48 more