feat: move "constants" to a separate object

api/gradle-ecj.api

@@ -1,3 +1,14 @@
+public final class io/github/themrmilchmann/gradle/ecj/ECJConstants {
+	public static final field INSTANCE Lio/github/themrmilchmann/gradle/ecj/ECJConstants;
+	public final fun getDEFAULT_DEPENDENCY_ARTIFACT ()Ljava/lang/String;
+	public final fun getDEFAULT_DEPENDENCY_GROUP ()Ljava/lang/String;
+	public final fun getDEFAULT_DEPENDENCY_VERSION ()Ljava/lang/String;
+	public final fun getECJ_CONFIGURATION_NAME ()Ljava/lang/String;
+	public final fun getMAIN ()Ljava/lang/String;
+	public final fun getPREFERRED_JAVA_VERSION ()I
+	public final fun getREQUIRED_JAVA_VERSION ()I
+}
+
 public abstract class io/github/themrmilchmann/gradle/ecj/ECJExtension {
 	public fun <init> (Lorg/gradle/api/model/ObjectFactory;)V
 	public final fun getCompilerArtifactId ()Lorg/gradle/api/provider/Property;
@@ -6,13 +17,6 @@ public abstract class io/github/themrmilchmann/gradle/ecj/ECJExtension {
 }
 
 public final class io/github/themrmilchmann/gradle/ecj/plugins/ECJPlugin : org/gradle/api/Plugin {
-	public static final field DEFAULT_DEPENDENCY_ARTIFACT Ljava/lang/String;
-	public static final field DEFAULT_DEPENDENCY_GROUP Ljava/lang/String;
-	public static final field DEFAULT_DEPENDENCY_VERSION Ljava/lang/String;
-	public static final field ECJ_CONFIGURATION_NAME Ljava/lang/String;
-	public static final field MAIN Ljava/lang/String;
-	public static final field PREFERRED_JAVA_VERSION I
-	public static final field REQUIRED_JAVA_VERSION I
 	public fun <init> ()V
 	public synthetic fun apply (Ljava/lang/Object;)V
 	public fun apply (Lorg/gradle/api/Project;)V

src/main/kotlin/io/github/themrmilchmann/gradle/ecj/ECJConstants.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2022-2023 Leon Linhart
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package io.github.themrmilchmann.gradle.ecj
+
+@Suppress("MayBeConstant")
+public object ECJConstants {
+
+    public val ECJ_CONFIGURATION_NAME: String = "ecj"
+
+    public val DEFAULT_DEPENDENCY_GROUP: String = "org.eclipse.jdt"
+    public val DEFAULT_DEPENDENCY_ARTIFACT: String = "ecj"
+    public val DEFAULT_DEPENDENCY_VERSION: String = "3.32.0"
+
+    public val MAIN: String = "org.eclipse.jdt.internal.compiler.batch.Main"
+
+    /* The version for which a toolchain is requested if the project's toolchain is not compatible. */
+    public val PREFERRED_JAVA_VERSION: Int = 17
+
+    /* The version required to run ECJ. */
+    public val REQUIRED_JAVA_VERSION: Int = 11
+
+}

src/main/kotlin/io/github/themrmilchmann/gradle/ecj/ECJExtension.kt

@@ -21,16 +21,15 @@
  */
 package io.github.themrmilchmann.gradle.ecj
 
-import io.github.themrmilchmann.gradle.ecj.plugins.ECJPlugin
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import javax.inject.Inject
 
 public abstract class ECJExtension @Inject constructor(objects: ObjectFactory) {
 
-    public val compilerGroupId: Property<String> = objects.property(String::class.java).convention(ECJPlugin.DEFAULT_DEPENDENCY_GROUP)
-    public val compilerArtifactId: Property<String> = objects.property(String::class.java).convention(ECJPlugin.DEFAULT_DEPENDENCY_ARTIFACT)
-    public val compilerVersion: Property<String> = objects.property(String::class.java).convention(ECJPlugin.DEFAULT_DEPENDENCY_VERSION)
+    public val compilerGroupId: Property<String> = objects.property(String::class.java).convention(ECJConstants.DEFAULT_DEPENDENCY_GROUP)
+    public val compilerArtifactId: Property<String> = objects.property(String::class.java).convention(ECJConstants.DEFAULT_DEPENDENCY_ARTIFACT)
+    public val compilerVersion: Property<String> = objects.property(String::class.java).convention(ECJConstants.DEFAULT_DEPENDENCY_VERSION)
 
     init {
         compilerGroupId.finalizeValueOnRead()

src/main/kotlin/io/github/themrmilchmann/gradle/ecj/plugins/ECJPlugin.kt

@@ -21,6 +21,10 @@
  */
 package io.github.themrmilchmann.gradle.ecj.plugins
 
+import io.github.themrmilchmann.gradle.ecj.ECJConstants.ECJ_CONFIGURATION_NAME
+import io.github.themrmilchmann.gradle.ecj.ECJConstants.MAIN
+import io.github.themrmilchmann.gradle.ecj.ECJConstants.PREFERRED_JAVA_VERSION
+import io.github.themrmilchmann.gradle.ecj.ECJConstants.REQUIRED_JAVA_VERSION
 import io.github.themrmilchmann.gradle.ecj.ECJExtension
 import io.github.themrmilchmann.gradle.ecj.internal.utils.*
 import org.gradle.api.*
@@ -34,21 +38,7 @@ import org.gradle.util.GradleVersion
 
 public class ECJPlugin : Plugin<Project> {
 
-    internal companion object {
-
-        const val ECJ_CONFIGURATION_NAME = "ecj"
-
-        const val DEFAULT_DEPENDENCY_GROUP = "org.eclipse.jdt"
-        const val DEFAULT_DEPENDENCY_ARTIFACT = "ecj"
-        const val DEFAULT_DEPENDENCY_VERSION = "3.32.0"
-
-        const val MAIN = "org.eclipse.jdt.internal.compiler.batch.Main"
-
-        /* The version for which a toolchain is requested if the project's toolchain is not compatible. */
-        const val PREFERRED_JAVA_VERSION = 17
-
-        /* The version required to run ECJ. */
-        const val REQUIRED_JAVA_VERSION = 11
+    private companion object {
 
         private val GRADLE_8_0 = GradleVersion.version("8.0")