RFR: 8354774: DocumentBuilderFactory getAttribute throws NPE [v3]

[Joe Wang]

> Fix a NPE on calling DocumentBuilderFactory::getAttribute, refer to the bug report.
> 
> Also in this patch: consolidates get and set properties to use the same Util methods to reduce potential errors when code changes.
> 
> Test:
>     Tier1 - 3 passed
>     JCK test passed

Joe Wang has updated the pull request incrementally with one additional commit since the last revision:

  adjust spaces

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24732/files
  - new: https://git.openjdk.org/jdk/pull/24732/files/1b8ecd32..022611dd

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24732&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24732&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24732.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24732/head:pull/24732

PR: https://git.openjdk.org/jdk/pull/24732