[birt-dev]CheckIn: Optimize the class TOCTreeNode, new the Object of Has

["Wei Wang" <wwang@xxxxxxxxxxx>]

Title: [birt-dev]CheckIn: Optimize the class TOCTreeNode, new the Object of HashSet lazily.

- Summary:
Optimize the class TOCTreeNode, new the Object of HashSet lazily.

- Bugzilla Bug (s) Resolved:
None

- Description:
In old version, we new an Object of HashSet with 16 capicity(default) when we new an Object of TOCTreeNode
it cost much memory when there are many groups, and it's one reason of OutOfMemory Exception.

- Tests Description  :
Unit Test & Manual Test

- Notes to Build Team:
None

- Notes to Developers:
None

- Notes to QA:  
None

- Notes to Documentation:  
None

- Files Edited:
"/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/toc/TOCTreeNode.java"

- Files Added:
None

- Files Deleted
None

- Wei Wang
Actuate Software(Shanghai) Co.,Ltd