[java] [7.0-rc1] ReplaceHashtableWithMap on java.util.Properties

[ben-manes]

Affects PMD Version:
7.0-rc1 upgrading from 6.55

Rule:
ReplaceHashtableWithMap

Description:
The rule suggests replacing when (a) the subtype cannot be replaced due to the api contract and (b) Properties now delegates to a ConcurrentHashMap. This rule should not apply to subtypes where the api is out of the author's control.

Code Sample demonstrating the issue:
JCache returns Properties in its api, so this code is flagged.

Expected outcome:
PMD reports a violation, but the user cannot make the suggested refactoring.

#	File	Line	Problem
1	jcache/CacheManagerImpl.java	48	Consider replacing this Hashtable with the newer java.util.Map

Running PMD through: Gradle
This requires workaround in gradle/gradle#24502

[road723]

JavaMail has a similar dependency on java.util.Properties so at least having this as a configurable property would be excellent