RFR: 8294948: Document IllegalArgumetException thrown by URLStreamHandler::parseURL and URLStreamHandler::setURL

Fri Oct 7 16:29:57 UTC 2022

During the review of JDK-8293590, it was noted that some methods in `URLStreamHandler` were missing an `@throws IllegalArgumentException` clause in their API documentation. 

This change adds the requested information, and also clarifies throwing `MalformedURLException` from URL constructors.

The CSR can be reviewed here: https://bugs.openjdk.org/browse/JDK-8294984

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Commit messages:
 - 8294948

Changes: https://git.openjdk.org/jdk/pull/10609/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10609&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294948
  Stats: 23 lines in 2 files changed: 20 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/10609.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10609/head:pull/10609

PR: https://git.openjdk.org/jdk/pull/10609