Update minimum support Java version from 8 to 11

[reta]

Hello!

We [1] have been using Mockito with JDK's SecurityManager (for historical reasons), the things worked fine for us till Mockito 4.8.0 release (and later versions). The culprit is Java9PlusLocationImpl (see please stack trace below):

Caused by: java.security.AccessControlException: access denied ("java.lang.RuntimePermission" "accessDeclaredMembers")
	at java.base/java.security.AccessControlContext.checkPermission(AccessControlContext.java:472)
	at java.base/java.security.AccessController.checkPermission(AccessController.java:897)
	at java.base/java.lang.SecurityManager.checkPermission(SecurityManager.java:322)
	at java.base/java.lang.Class.checkMemberAccess(Class.java:2847)
	at java.base/java.lang.Class.getDeclaredMethod(Class.java:2471)
	at org.mockito.internal.debugging.Java9PlusLocationImpl.stackWalker(Java9PlusLocationImpl.java:191)
	at org.mockito.internal.debugging.Java9PlusLocationImpl.<clinit>(Java9PlusLocationImpl.java:50)
	... 47 more

By all means, Mockito should know nothing about SecurityManager and the way we implemented mocking under SecurityManager is by using Mockito's extensibility model - plugins (primary, MockMaker). Sadly for LocationFactory / Location there is no such plugin available so we are stuck on 4.7.x release line. If such plugin would have been available, we could provide privileged implementation for reflection calls. Alternatively, wrapping up Java 9 implementation into multi-release JAR (and getting rid of reflection), would have helped.

We are happy to submit the pull request with either solution, but it would be helpful to know if there is an interest addressing this issue in general, and preferred approach in particular:

• plugin for LocationFactory / Location
• multi-release JAR for Java 9

Thank you.

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[1] https://github.com/opensearch-project/OpenSearch

[TimvdLippe]

As a third option, we can also drop Java 8, so that we can import the StackWalker directly.

I am not sure what's best. A plugin for the LocationFactory sounds a bit weird, as that is internal to Mockito and how it works. A multi-release jar, I am not sure how well this will integrate with the build systems of our users and I am afraid that we might inadvertently break them.

@mockito/developers We have been hitting several Java 8 issues lately and this is yet another one where we have to workaround Java 8 to support modern JDK versions. WDYT of upgrading to Java 11 as a minimum requirement? I can create a separate issue for that if you want.

[raphw]

I think it's fair to move on to Java 11. Today Spring 6 arrived which baselines to Java 17, we are not even on the edge of things with this in mind, so thumbs up for bumping to 11.

[reta]

@raphw that's unexpected win-win outcome :-), thanks @TimvdLippe for this 3rd option, I can take it (under new issue) if no one is working on it at the moment.

[TimvdLippe]

I filed #2802 to consolidate the changes for Mockito 5. For this issue, we will need to:

• Bump our minimum Java version to 11 specified here:

  mockito/gradle/java-library.gradle

  Lines 17 to 18 in 0ce902a

  	sourceCompatibility = 1.8
  	targetCompatibility = 1.8

• Additionally, we can look into remove our JavaDoc hack (https://github.com/mockito/mockito/tree/main/gradle/mockito-core/java-8-docs) which effectively reverts Possible fix #2765: Add task to download package-list file from java as element-list #2766
• We need to update our version of JavaDoc here:

  mockito/gradle/mockito-core/javadoc.gradle

  Line 48 in 0ce902a

  options.linksOffline('https://docs.oracle.com/javase/8/docs/api/', java8DocsDir)

• Remove 8 from our build matrix:

  mockito/.github/workflows/ci.yml

  Line 32 in 0ce902a

  java: [8, 11, 17]

• Update all matrix checks to run on 11 instead:

  mockito/.github/workflows/ci.yml

  Line 51 in 0ce902a

  if: matrix.java == 8 && matrix.mock-maker == 'mock-maker-default' # SINGLE-MATRIX-JOB

• Remove all checks in .gradle files that check for Version 8 explicitly:

  mockito/subprojects/module-test/module-test.gradle

  Line 5 in 0ce902a

  if (JavaVersion.current() == JavaVersion.VERSION_1_8) {

• Remove all checks in .gradle files that check if we are Java 9 compatible:

  mockito/subprojects/inline/inline.gradle

  Line 17 in 0ce902a

  if (JavaVersion.current().java9Compatible) {

We can clean up the source code in src/main/java to remove all reflection usages (and thus solve this ticket) in Mockito 5.1.0. I would prefer to make it a clean cut first, so that upgrading is relatively straightforward. Then fixes go in a minor release, so that we can catch regressions separately.

Let me know if you think I missed something. I would welcome some PRs to get these fixed!