Make CSI plugin collect too much classpaths

.gitignore

@@ -77,3 +77,6 @@ mise*.local.toml
 .config/mise*.toml
 # asdf
 .tool-versions
+
+# Exclude kotlin build files
+.kotlin

buildSrc/build.gradle.kts

@@ -24,7 +24,7 @@ gradlePlugin {
     }
     create("call-site-instrumentation-plugin") {
       id = "call-site-instrumentation"
-      implementationClass = "datadog.gradle.plugin.CallSiteInstrumentationPlugin"
+      implementationClass = "datadog.gradle.plugin.csi.CallSiteInstrumentationPlugin"
     }
     create("tracer-version-plugin") {
       id = "datadog.tracer-version"

buildSrc/call-site-instrumentation-plugin/src/main/java/datadog/trace/plugin/csi/util/CallSiteUtils.java

@@ -3,6 +3,7 @@
 import java.io.File;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
@@ -47,7 +48,20 @@ public static String repeat(final char value, int count) {
 
   public static URL toURL(final Path path) {
     try {
-      return path.toUri().toURL();
+      URL url = path.toUri().toURL();
+      // URLClassLoader interprets URLs ending with '/' as directories. If the trailing '/' is
+      // missing, a directory URL is treated as a JAR. If the path does yet exist on disk
+      // assumes that paths not ending with ".jar" are directories.
+      boolean shouldAddSlash =
+          Files.exists(path) ? Files.isDirectory(path) : !path.toString().endsWith(".jar");
+
+      if (shouldAddSlash) {
+        String urlString = url.toString();
+        if (!urlString.endsWith("/")) {
+          url = new URL(urlString + "/");
+        }
+      }
+      return url;
     } catch (MalformedURLException e) {
       throw new RuntimeException(e);
     }

buildSrc/src/main/kotlin/datadog/gradle/plugin/csi/CallSiteInstrumentationExtension.kt

@@ -0,0 +1,83 @@
+package datadog.gradle.plugin.csi
+
+import org.gradle.api.file.ConfigurableFileCollection
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.file.ProjectLayout
+import org.gradle.api.model.ObjectFactory
+import org.gradle.api.provider.ListProperty
+import org.gradle.api.provider.Property
+import org.gradle.jvm.toolchain.JavaLanguageVersion
+import org.gradle.kotlin.dsl.listProperty
+import org.gradle.kotlin.dsl.property
+import java.io.File
+import javax.inject.Inject
+
+
+/**
+ * This extension allows to configure the Call Site Instrumenter plugin execution.
+ */
+abstract class CallSiteInstrumentationExtension @Inject constructor(
+  objectFactory: ObjectFactory,
+  layout: ProjectLayout
+) {
+  companion object {
+    const val CALL_SITE_CLASS_SUFFIX = "CallSite"
+    const val CALL_SITE_CONSOLE_REPORTER = "CONSOLE"
+    const val CALL_SITE_ERROR_CONSOLE_REPORTER = "ERROR_CONSOLE"
+  }
+
+  /**
+   * The location of the source code to generate call site ({@code <project>/src/main/java} by default).
+   */
+  val srcFolder: DirectoryProperty = objectFactory.directoryProperty().convention(
+    layout.projectDirectory.dir("src").dir("main").dir("java")
+  )
+
+  /**
+   * The location to generate call site source code ({@code <project>/build/generated/sources/csi} by default).
+   */
+  val targetFolder: DirectoryProperty = objectFactory.directoryProperty().convention(
+    layout.buildDirectory.dir("generated/sources/$CSI_SOURCE_SET")
+  )
+
+  /**
+   * The generated call site source file suffix (#CALL_SITE_CLASS_SUFFIX by default).
+   */
+  val suffix: Property<String> = objectFactory.property<String>().convention(CALL_SITE_CLASS_SUFFIX)
+
+  /**
+   * The reporters to use after call site instrumenter run (only #CALL_SITE_CONSOLE_REPORTER and #CALL_SITE_ERROR_CONSOLE_REPORTER supported for now).
+   */
+  val reporters: ListProperty<String> = objectFactory.listProperty<String>().convention(
+    listOf(
+      CALL_SITE_ERROR_CONSOLE_REPORTER
+    )
+  )
+
+  /**
+   * The location of the dd-trace-java project to look for the call site instrumenter (optional, current project root folder used if not set).
+   */
+  abstract val rootFolder: Property<File>
+
+  /**
+   * The JVM to use to run the call site instrumenter (optional, default JVM used if not set).
+   */
+  val javaVersion: Property<JavaLanguageVersion> =
+    objectFactory.property<JavaLanguageVersion>().convention(JavaLanguageVersion.current())
+
+  /**
+   * The JVM arguments to run the call site instrumenter.
+   */
+  val jvmArgs: ListProperty<String> =
+    objectFactory.listProperty<String>().convention(listOf("-Xmx128m", "-Xms64m"))
+
+  /**
+   * The paths used to look for the call site instrumenter dependencies.
+   *
+   * The plugin includes by default **only** the `main` and `test` source sets, and their
+   * related compilation classpath. As we don't want other test configurations by default.
+   *
+   * However, it's possible to contribute additional paths to look for dependencies.
+   */
+  val additionalPaths: ConfigurableFileCollection = objectFactory.fileCollection()
+}