[jdk11u-dev] RFR: 8248001: javadoc generates invalid HTML pages whose ftp:// links are broken

[ktakakuri]

I would like to backport
8248001: javadoc generates invalid HTML pages whose ftp:// links are broken.
There are minor differences regarding DocRoot, but otherwise this is a clean backport.

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Commit messages:
 - Backport bb95dda0ac5032e4df582f2903dcbbbbaef9e8c4

Changes: https://git.openjdk.org/jdk11u-dev/pull/2002/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2002&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8248001
  Stats: 79 lines in 3 files changed: 76 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2002.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2002/head:pull/2002

PR: https://git.openjdk.org/jdk11u-dev/pull/2002