the actual Gradle fixes were trivial

diff --git a/build.gradle b/build.gradle
index 8fd6d27a49..20c6c2461c 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,16 +1,14 @@
 buildscript {
     repositories {
-        jcenter()
+        mavenCentral()
     }
     dependencies {
-        classpath 'edu.sc.seis.gradle:launch4j:2.4.4'
         classpath 'net.sf.proguard:proguard-gradle:6.1.0'
     }
 }
 
 apply plugin: 'java'
 apply plugin: 'distribution'
-apply plugin: 'edu.sc.seis.launch4j'
 
 // Common configuration //
 rootProject.version='1.6.6'
@@ -29,7 +27,7 @@
     }
 
     repositories {
-        jcenter()
+        mavenCentral()
     }
 
     configurations {
@@ -105,16 +103,3 @@
     libraryjars System.getProperty('java.home') + '/lib/rt.jar'
     libraryjars System.getProperty('java.home') + '/jmods/'
 }
-
-// Java executable wrapper for Windows //
-launch4j {
-    createExe.dependsOn 'proguard'
-
-    version = textVersion = project.version
-    fileDescription = productName = 'JD-GUI'
-    errTitle 'JD-GUI Windows Wrapper'
-    copyright 'JD-GUI (C) 2008-2019 Emmanuel Dupuy'
-    icon projectDir.path + '/src/launch4j/resources/images/jd-gui.ico'
-    jar projectDir.path + '/' + proguard.outJarFiles[0]
-    bundledJrePath = '%JAVA_HOME%'
-}

In reply to@emilazy:matrix.org
merged; did you want to open a gradle_6 drop?

In reply to@emilazy:matrix.org
oh I forgot we didn't merge that one :)

In reply to@tomodachi94:matrix.org
https://github.com/NixOS/nixpkgs/pull/352490

In reply to@emilazy:matrix.org
it's a strong source IMO

For major versions, Gradle will backport critical fixes and security fixes to the last minor in the previous major version. For example, when Gradle 7 was the latest major version, several releases were made in the 6.x line, including Gradle 6.9 (and subsequent releases).

The major version before the previous one to become end-of-life (EOL), and that release line will not receive any new fixes.