Clean up initial files

build.gradle

@@ -49,7 +49,7 @@ gradlePlugin {
             id = "org.embulk.runset"
             displayName = "A Gradle plugin to prepare an environment for running Embulk"
             description = "${project.description}"
-            implementationClass = "org.embulk.gradle.runset.RunsetPlugin"
+            implementationClass = "org.embulk.gradle.runset.EmbulkRunSetPlugin"
             tags = ["embulk"]
         }
     }

src/main/java/org/embulk/gradle/runset/RunsetPlugin.java → src/main/java/org/embulk/gradle/runset/EmbulkRunSetPlugin.java

@@ -20,14 +20,10 @@
 import org.gradle.api.Project;
 
 /**
- * A Gradle plugin to prepare an environment for running Embulk.
+ * A Gradle plugin to set up an environment for running Embulk.
  */
-public class RunsetPlugin implements Plugin<Project> {
+public class EmbulkRunSetPlugin implements Plugin<Project> {
     @Override
     public void apply(final Project project) {
-        project.getExtensions().create(
-                "embulkRunset",
-                EmbulkRunsetExtension.class,
-                project);
     }
 }

src/test/java/org/embulk/gradle/runset/TestRunsetPlugin.java → src/test/java/org/embulk/gradle/runset/TestEmbulkRunSetPlugin.java

@@ -23,7 +23,7 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
-public class TestRunsetPlugin  {
+public class TestEmbulkRunSetPlugin  {
     @Test
     public void test(@TempDir Path tempDir) throws IOException {
         assertEquals(true, true);