Add --gradle-jdk argument

app/src/main/kotlin/org/nixos/gradle2nix/GradleRunner.kt

@@ -23,6 +23,9 @@ fun ProjectConnection.build(
             } else {
                 forTasks(RESOLVE_ALL_TASK)
             }
+            if (config.gradleJdk != null) {
+                setJavaHome(config.gradleJdk)
+            }
             addArguments(config.gradleArgs)
             addArguments(
                 "--init-script=${config.appHome}/init.gradle",

app/src/main/kotlin/org/nixos/gradle2nix/Main.kt

@@ -20,6 +20,7 @@ data class Config(
     val appHome: File,
     val gradleHome: File,
     val gradleVersion: String?,
+    val gradleJdk: File?,
     val gradleArgs: List<String>,
     val projectFilter: String?,
     val configurationFilter: String?,
@@ -43,6 +44,12 @@ class Gradle2Nix : CliktCommand(
         help = "Use a specific Gradle version"
     )
 
+    private val gradleJdk: File? by option(
+        "--gradle-jdk", "-j",
+        metavar = "DIR",
+        help = "JDK home directory to use for launching Gradle (default: ${System.getProperty("java.home")})"
+    ).file(canBeFile = false, canBeDir = true)
+
     private val projectFilter: String? by option(
         "--projects", "-p",
         metavar = "REGEX",
@@ -115,6 +122,7 @@ class Gradle2Nix : CliktCommand(
             File(appHome),
             gradleHome,
             gradleVersion,
+            gradleJdk,
             gradleArgs,
             projectFilter,
             configurationFilter,