Try to workaround a lock by using the Plugin instance when constructing the HistoryDao:
"Trigger.init":
  waiting to lock Monitor@0x00007f9557abab38 (Object@0x0000000127076730, a hudson/DescriptorExtensionList),
  which is held by "UpdateCenter.init"
"UpdateCenter.init":
  waiting to lock Monitor@0x00007f9557ab9c18 (Object@0x0000000127539b50, a hudson/ExtensionList$Lock),
  which is held by "Trigger.init"