RFR: 8273401: Disable JarIndex support in URLClassPath

[Lance Andersen]

On Wed, 15 Sep 2021 15:48:55 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>>> Another question is where to document this property. We will obviously need a CSR and releases notes. I also wonder if it should be promoted into a networking property - which would make it possible to document it in the `net.properties` file. @AlanBateman what do you think?
>> 
>> jdk.net.URLClassLoader.enableJarIndex is meant to be a temporary property. We could document it in URLClassLoader as an implNote but I'm not sure that it's worth it. I re-worded the CSR to reflect the current proposal and Wang has submitted it.  I noted in the CSR that a release note is planned.
>
>> Maybe this should use the same pattern than the other property above:
>> 
>> ```
>> ENABLE_JAR_INDEX = p != null ? p.equals("true") || p.isEmpty() : false;
>> ```
> 
> Yes, the intention is that -Djdk.net.URLClassLoader.enableJarIndex will re-enable the feature.

I assume the reason for specifically checking for a value of true or an empty string as you envision allowing the property to be explicitly set to false in the future?  

Otherwise we could just check if the property is set(regardless of value) to re-enable the feature.

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PR: https://git.openjdk.java.net/jdk/pull/5524