Override SystemReader#openSystemConfig instead of getenv

- Apply Java plugin for buildSrc

Author: Choonster

buildSrc/build.gradle

@@ -1,7 +1,11 @@
+plugins {
+    id 'java'
+}
+
 repositories {
     mavenCentral();
 }
 
 dependencies {
-    implementation "org.eclipse.jgit:org.eclipse.jgit:7.4.0.202509020913-r"
+    implementation 'org.eclipse.jgit:org.eclipse.jgit:7.4.0.202509020913-r'
 }

buildSrc/src/main/java/choonster/testmod3/gradle/NoSystemConfigSystemReader.java

@@ -1,10 +1,10 @@
 package choonster.testmod3.gradle;
 
-import org.eclipse.jgit.lib.Constants;
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.storage.file.FileBasedConfig;
+import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.SystemReader;
 
-import java.util.Objects;
-
 /**
  * A {@link SystemReader} implementation that disables reading of system config.
  *
@@ -16,11 +16,19 @@ public NoSystemConfigSystemReader(final SystemReader delegate) {
 	}
 
 	@Override
-	public String getenv(final String variable) {
-		if (Objects.equals(variable, Constants.GIT_CONFIG_NOSYSTEM_KEY)) {
-			return "true";
-		}
+	public FileBasedConfig openSystemConfig(final Config parent, final FS fs) {
+		// Based on the SystemReader.Default#openSystemConfig implementation
+		return new FileBasedConfig(parent, null, fs) {
+			@Override
+			public void load() {
+				// empty, do not load
+			}
 
-		return super.getenv(variable);
+			@Override
+			public boolean isOutdated() {
+				// regular class would bomb here
+				return false;
+			}
+		};
 	}
 }