RFR: 8302791: Add specific ClassLoader object to Proxy IllegalArgumentException message

[Ravali Yatham]

Added specific class loader object to proxy IllegalArgumentException from which the class was not visible

The bug report for the same: https://bugs.openjdk.org/browse/JDK-8302791

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Commit messages:
 - Added specific ClassLoader object to Proxy IllegalArgumentException

Changes: https://git.openjdk.org/jdk/pull/12641/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12641&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302791
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12641.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12641/head:pull/12641

PR: https://git.openjdk.org/jdk/pull/12641