test(appsec): add earlyDep10ForkedTest to cover Jetty 10.0.0–10.0.9

The jetty-appsec-9.4 early_10_series muzzle pass covers [10.0.0, 10.0.10)
where _multiParts is MultiPartFormInputStream (before the type changed to
MultiParts in 10.0.10). The existing test suite used 10.0.10, leaving the
early versions untested.

Add earlyDep10ForkedTest (Jetty 10.0.9) to exercise the OR-muzzle reference
and verify that multipart filename events fire correctly on the old field type.
All three filename tests pass: filenames, filenames-called-once, filenames-combined.

Author: jandro996

dd-java-agent/instrumentation/jetty/jetty-server/jetty-server-10.0/build.gradle

@@ -36,6 +36,9 @@ tracerJava {
 
 addTestSuiteForDir("latestDepTest", "test")
 addTestSuiteExtendingForDir("latestDepForkedTest", "latestDepTest", "test")
+// Exercises jetty-appsec-9.4's early_10_series muzzle pass: _multiParts was
+// MultiPartFormInputStream in [10.0.0, 10.0.10) before switching to MultiParts in 10.0.10.
+addTestSuiteForDir("earlyDep10ForkedTest", "test")
 
 dependencies {
   main_java11Implementation project(':dd-java-agent:instrumentation:jetty:jetty-common')
@@ -82,6 +85,17 @@ dependencies {
   latestDepForkedTestImplementation group: 'org.eclipse.jetty.websocket', name: 'websocket-javax-server', version: '10.+'
   latestDepForkedTestImplementation project(':dd-java-agent:instrumentation:jetty:jetty-appsec:jetty-appsec-9.4')
   latestDepForkedTestImplementation testFixtures(project(':dd-java-agent:instrumentation:servlet:javax-servlet:javax-servlet-3.0'))
+
+  // Early Jetty 10 (10.0.0–10.0.9): _multiParts is MultiPartFormInputStream, not MultiParts.
+  earlyDep10ForkedTestImplementation group: 'org.eclipse.jetty', name: 'jetty-server', version: '10.0.9'
+  earlyDep10ForkedTestImplementation group: 'org.eclipse.jetty', name: 'jetty-servlet', version: '10.0.9'
+  earlyDep10ForkedTestImplementation group: 'org.eclipse.jetty.websocket', name: 'websocket-javax-server', version: '10.0.9'
+  earlyDep10ForkedTestImplementation project(':dd-java-agent:instrumentation:jetty:jetty-appsec:jetty-appsec-9.4')
+  earlyDep10ForkedTestImplementation testFixtures(project(':dd-java-agent:instrumentation:servlet:javax-servlet:javax-servlet-3.0'))
+}
+
+tasks.named('earlyDep10ForkedTest', Test) {
+  systemProperty 'test.dd.earlyJetty10', 'true'
 }
 
 configurations.named('latestDepForkedTestRuntimeClasspath') {

dd-java-agent/instrumentation/jetty/jetty-server/jetty-server-10.0/src/test/groovy/datadog/trace/instrumentation/jetty10/Jetty10EarlyDepForkedTest.groovy

@@ -0,0 +1,29 @@
+package datadog.trace.instrumentation.jetty10
+
+import datadog.trace.agent.test.naming.TestingGenericHttpNamingConventions
+import spock.lang.Requires
+
+/**
+ * Exercises jetty-appsec-9.4's "early_10_series" muzzle pass ([10.0.0, 10.0.10)) where
+ * {@code _multiParts} is {@code MultiPartFormInputStream} instead of {@code MultiParts}.
+ * The OR-muzzle reference in jetty-appsec-9.4 covers both field types; this suite
+ * verifies the advice actually applies and fires AppSec events on the older field type.
+ *
+ * <p>Guarded by the {@code test.dd.earlyJetty10} system property so these classes
+ * only run in the {@code earlyDep10ForkedTest} Gradle task (Jetty 10.0.9).
+ */
+@Requires({
+  System.getProperty('test.dd.earlyJetty10')
+})
+class Jetty10EarlyDepV0ForkedTest extends Jetty10Test implements TestingGenericHttpNamingConventions.ServerV0 {
+}
+
+@Requires({
+  System.getProperty('test.dd.earlyJetty10')
+})
+class Jetty10EarlyDepV1ForkedTest extends Jetty10Test implements TestingGenericHttpNamingConventions.ServerV1 {
+  @Override
+  protected boolean useWebsocketPojoEndpoint() {
+    false
+  }
+}