IssueTracker

- Studio Build: AI-191.8026.42.35.6010548
- Version of Gradle Plugin: com.android.tools.build:gradle:3.5.1
- Version of Gradle: 6.1.1
- Version of Java: Adopt Open JDK 1.8.0_242
- OS: Ubuntu 18.04.4 LTS

Prerequesites:
- Local Gradle 6.1.1 installation, e.g. at /opt/devenv/gradle

Steps to Reproduce:
1. Import a clean Android library Gradle project into Android Studio (AS). The project only contains a build.gradle and no Gradle wrapper
2. AS opens the "Gradle Sync" dialog -> cancel to select local Gradle installation
3. AS opens "Import Gradle Project" dialog to select Gradle home location -> enter /opt/devenv/gradle
4. AS complains "Gradle 5.4.1 or newer is required"

Debugging:
- Problem is located in AS/plugins/android/lib/android.jar
- com.android.tools.idea.gradle.util.GradleVersions
  - has a Problem to identify the Gradle version in the local Gradle installation
  - Line 108: libFolderPath.listFiles() -> under Ubuntu this Java call returns an unsorted file list
  - When iterating over this file list -> gradle-core-api-6.1.1.jar has a lower index then gradle-core-6.1.1.jar
  - Line 122: the Pattern ("gradle-core-(.*)\\.jar") matches "gradle-core-api-6.1.1.jar" as a valid file
  - Line 125: returns matching group(1) as version -> "api-6.1.1"
  - Line 134: finally removeTimestampFromGradleVersion returns -> "api"
- com.android.tools.idea.gradle.project.ChooseGradleHomeDialog
  - Line 152: there is a version compare in the dialog GradleVersion("5.4.1").compareTo(GradleVersion("api")) = 5 > 0
  - This results in the error message
 
Solution:
- GradleVersions has to fix the Pattern matcher to identify the proper Gradle version in a local Gradle installation

Additional info:
- Java File.listFiles() seems to return an alphabetically sorted list under Windows, so the error did not occur there, since gradle-core-6.1.1.jar is identified properly
- I already reported the problem https://issuetracker.google.com/issues/140055779 but seems not be taken serious or fixed so far(?)