RFR: 8071693: Introspector ignores default interface methods [v6]

[Archie Cobbs]

> The `Introspector` class was never updated to include `default` methods inherited from interfaces.
> 
> This patch attempts to fix that omission.

Archie Cobbs has updated the pull request incrementally with one additional commit since the last revision:

  Add braces around if clause.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13544/files
  - new: https://git.openjdk.org/jdk/pull/13544/files/ac90a10e..8c129960

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13544&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13544&range=04-05

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13544.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13544/head:pull/13544

PR: https://git.openjdk.org/jdk/pull/13544