RFR: 8332096: hotspot-ide-project fails with this-escape

[Alex Menkov]

The change fixes `make hotspot-ide-project` which fails with

\open\make\ide\visualstudio\hotspot\src\classes\build\tools\projectcreator\FileTreeCreator.java:54: warning: [this-escape] possible 'this' escape before subclass is fully initialized
      attributes.push(new DirAttributes());
                      ^
error: warnings found and -Werror specified

-------------

Commit messages:
 - fix

Changes: https://git.openjdk.org/jdk/pull/19186/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19186&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8332096
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19186.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19186/head:pull/19186

PR: https://git.openjdk.org/jdk/pull/19186