[jdk17] RFR: JDK-8266269: Lookup::accessClass fails with IAE when accessing an arrayClass with a protected inner class as component class

[Mandy Chung]

`Lookup::accessClass` should determine the accessibility of the element type.  An array class is accessible if and only if its element type is accessible.

This also fixes a spec bug to document `@throws NullPointerException` if the argument is null.

Please review the CSR:
    https://bugs.openjdk.java.net/browse/JDK-8269312

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Commit messages:
 - fix whitespace
 - JDK-8266269:  Lookup::accessClass fails with IAE when accessing an arrayClass with a protected inner class as component class

Changes: https://git.openjdk.java.net/jdk17/pull/137/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=137&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8266269
  Stats: 103 lines in 5 files changed: 85 ins; 2 del; 16 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/137.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/137/head:pull/137

PR: https://git.openjdk.java.net/jdk17/pull/137