RFR: 8270380: Change the default value of the java.security.manager system property to disallow

[Weijun Wang]

On Fri, 20 Aug 2021 22:44:34 GMT, Weijun Wang <weijun at openjdk.org> wrote:

> This change modifies the default value of the `java.security.manager` system property from "allow" to "disallow". This means unless it's explicitly set to "allow", any call to `System.setSecurityManager()` would throw an UOE.
> 
> The `AllowSecurityManager.java` and `SecurityManagerWarnings.java` tests are updated to confirm this behavior change. Two other tests are updated because they were added after JDK-8267184 and do not have `-Djava.security.manager=allow` on its `@run` line even it they need to install a `SecurityManager` at runtime.
> 
> Please note that this code change requires jtreg to be upgraded to 6.1, where a security manager [will not be set](https://bugs.openjdk.java.net/browse/CODETOOLS-7902990).

This issue (https://bugs.openjdk.java.net/browse/JDK-8270380) is blocked by jtreg 6.1 (https://bugs.openjdk.java.net/browse/CODETOOLS-7902990). Precisely, it should be blocked by a JDK bug that updates the jtreg required version to 6.1.

I should have mentioned this in the PR.

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PR: https://git.openjdk.java.net/jdk/pull/5204