Merge pull request #26452 Fix order dependency in excluded group

Signed-off-by: K Ke \ [email protected]

### Context
HashSet default iteration order changed between Java 7 and 8, breaking lots of unit tests. Our NonDex plugin https://github.com/TestingResearchIllinois/NonDex permutes these orders just as between Java 7 and 8, and it triggers the following error when testing the Gradle building process of a plugin repeatedly:
```
org.gradle.api.InvalidUserCodeException: Cannot change default excludes during the build. They were changed from [foo, bar, xyz] to [foo, bar, xyz]
```

### Reason
`PatternSpecFactory` is making sure that excluded group is not changed during the build process. In line 91 of `PatternSpecFactory.java`, `DirectoryScanner.getDefaultExcludes()` is called to get the list of excluded groups in String format. However, it can be see that Ant simply casted their `HashSet` of `defaultExcludes` to `Array` in their implementation of  `getDefaultExcludes()` (See https://github.com/apache/ant/blob/72d6a274733d7c5460efc9ae53d645246184dabe/src/main/org/apache/tools/ant/DirectoryScanner.java#L571). However, Oracle document specifies that `HashSet` does not ensure iteration order (https://docs.oracle.com/javase/8/docs/api/java/util/HashSet.html), so the returned Array of `getDefaultExcludes()` does not ensure order. Therefore, if we run a "assert Gradle build success for plugin" unit test repeatedly, we can trigger `invalidChangeOfExcludes()` (line 102 in `PatternSpecFactory.java`) as the array of excluded group strings may have order permutation.

### Significance of Fixing
The HashMap and HashSet default iteration order did change between Java 7 and 8, and may change again in the future, even if it appears deterministic now. Moreover, the list of `excluded files` should not rely on any order by nature.

### Suggested Fix
Convert the `Array` of excluded groups to `HashSet` before comparison. This is efficient with O(n+n) runtime - it will not increase overhead as much as `sort()` would.

### Contributor Checklist
- [X] [Review Contribution Guidelines](https://github.com/gradle/gradle/blob/master/CONTRIBUTING.md)
- [X] Make sure that all commits are [signed off](https://git-scm.com/docs/git-commit#Documentation/git-commit.txt---signoff) to indicate that you agree to the terms of [Developer Certificate of Origin](https://developercertificate.org/).
- [X] Make sure all contributed code can be distributed under the terms of the [Apache License 2.0](https://github.com/gradle/gradle/blob/master/LICENSE), e.g. the code was written by yourself or the original code is licensed under [a license compatible to Apache License 2.0](https://apache.org/legal/resolved.html).
- [X] Check ["Allow edit from maintainers" option](https://help.github.com/articles/allowing-changes-to-a-pull-request-branch-created-from-a-fork/) in pull request so that additional changes can be pushed by Gradle team
- [ ] Provide integration tests (under `<subproject>/src/integTest`) to verify changes from a user perspective
- [ ] Provide unit tests (under `<subproject>/src/test`) to verify logic
- [ ] Update User Guide, DSL Reference, and Javadoc for public-facing changes
- [X] Ensure that tests pass sanity check: `./gradlew sanityCheck`
- [X] Ensure that tests pass locally: `./gradlew <changed-subproject>:quickTest`

### Reviewing cheatsheet

Before merging the PR, comments starting with
- ❌ ❓**must** be fixed
- 🤔 💅 **should** be fixed
- 💭 **may** be fixed
- 🎉 celebrate happy things

Co-authored-by: Kaiyao Ke <[email protected]>

subprojects/core-api/src/main/java/org/gradle/api/tasks/util/internal/PatternSpecFactory.java

@@ -34,8 +34,10 @@
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.EnumMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * The basic implementation for converting {@link PatternSet}s to {@link Spec}s.
@@ -46,7 +48,7 @@
 @ServiceScope(Scope.Global.class)
 public class PatternSpecFactory implements FileSystemDefaultExcludesListener {
     public static final PatternSpecFactory INSTANCE = new PatternSpecFactory();
-    private String[] previousDefaultExcludes;
+    private Set<String> previousDefaultExcludes = new HashSet<String>();
     private final Map<CaseSensitivity, Spec<FileTreeElement>> defaultExcludeSpecCache = new EnumMap<>(CaseSensitivity.class);
 
     @Override
@@ -88,7 +90,7 @@ public Spec<FileTreeElement> createExcludeSpec(PatternSet patternSet) {
     }
 
     private synchronized Spec<FileTreeElement> getDefaultExcludeSpec(CaseSensitivity caseSensitivity) {
-        String[] defaultExcludes = DirectoryScanner.getDefaultExcludes();
+        Set<String> defaultExcludes = new HashSet<String>(Arrays.asList(DirectoryScanner.getDefaultExcludes()));
         if (defaultExcludeSpecCache.isEmpty()) {
             updateDefaultExcludeSpecCache(defaultExcludes);
         } else if (invalidChangeOfExcludes(defaultExcludes)) {
@@ -98,29 +100,29 @@ private synchronized Spec<FileTreeElement> getDefaultExcludeSpec(CaseSensitivity
         return defaultExcludeSpecCache.get(caseSensitivity);
     }
 
-    private boolean invalidChangeOfExcludes(String[] defaultExcludes) {
-        return !Arrays.equals(previousDefaultExcludes, defaultExcludes);
+    private boolean invalidChangeOfExcludes(Set<String> defaultExcludes) {
+        return !previousDefaultExcludes.equals(defaultExcludes);
     }
 
-    private void failOnChangedDefaultExcludes(String[] excludesFromSettings, String[] newDefaultExcludes) {
-        List<String> sortedExcludesFromSettings = Arrays.asList(excludesFromSettings);
+    private void failOnChangedDefaultExcludes(Set<String> excludesFromSettings, Set<String> newDefaultExcludes) {
+        List<String> sortedExcludesFromSettings = new ArrayList<String>(excludesFromSettings);
         sortedExcludesFromSettings.sort(Comparator.naturalOrder());
-        List<String> sortedNewExcludes = Arrays.asList(newDefaultExcludes);
+        List<String> sortedNewExcludes = new ArrayList<String>(newDefaultExcludes);
         sortedNewExcludes.sort(Comparator.naturalOrder());
         throw new InvalidUserCodeException(String.format("Cannot change default excludes during the build. They were changed from %s to %s. Configure default excludes in the settings script instead.",  sortedExcludesFromSettings, sortedNewExcludes));
     }
 
     public synchronized void setDefaultExcludesFromSettings(String[] excludesFromSettings) {
-        if (!Arrays.equals(previousDefaultExcludes, excludesFromSettings)) {
-            updateDefaultExcludeSpecCache(excludesFromSettings);
+        Set<String> excludesFromSettingsSet = new HashSet<String>(Arrays.asList(excludesFromSettings));
+        if (!previousDefaultExcludes.equals(excludesFromSettingsSet)) {
+            updateDefaultExcludeSpecCache(excludesFromSettingsSet);
         }
     }
 
-    private void updateDefaultExcludeSpecCache(String[] defaultExcludes) {
+    private void updateDefaultExcludeSpecCache(Set<String> defaultExcludes) {
         previousDefaultExcludes = defaultExcludes;
-        List<String> patterns = Arrays.asList(defaultExcludes);
         for (CaseSensitivity caseSensitivity : CaseSensitivity.values()) {
-            defaultExcludeSpecCache.put(caseSensitivity, createSpec(patterns, false, caseSensitivity.isCaseSensitive()));
+            defaultExcludeSpecCache.put(caseSensitivity, createSpec(defaultExcludes, false, caseSensitivity.isCaseSensitive()));
         }
     }