Avoid eagerly resolving entitlement agent during test task configuration (elastic#133678)

Author: mark-vieira

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/ElasticsearchTestBasePlugin.java

@@ -330,24 +330,22 @@ private static void configureEntitlements(Project project) {
             .matching(test -> TEST_TASKS_WITH_ENTITLEMENTS.contains(test.getName()))
             .configureEach(test -> {
                 // See also SystemJvmOptions.maybeAttachEntitlementAgent.
+                SystemPropertyCommandLineArgumentProvider nonInputSystemProperties = test.getExtensions()
+                    .getByType(SystemPropertyCommandLineArgumentProvider.class);
 
                 // Agent
-                if (agentFiles.isEmpty() == false) {
-                    test.getInputs().files(agentFiles);
-                    test.systemProperty("es.entitlement.agentJar", agentFiles.getAsPath());
-                    test.systemProperty("jdk.attach.allowAttachSelf", true);
-                }
+                test.getInputs().files(agentFiles).optional(true);
+                nonInputSystemProperties.systemProperty("es.entitlement.agentJar", agentFiles::getAsPath);
+                nonInputSystemProperties.systemProperty("jdk.attach.allowAttachSelf", () -> agentFiles.isEmpty() ? "false" : "true");
 
                 // Bridge
-                if (bridgeFiles.isEmpty() == false) {
-                    String modulesContainingEntitlementInstrumentation = "java.logging,java.net.http,java.naming,jdk.net";
-                    test.getInputs().files(bridgeFiles);
-                    // Tests may not be modular, but the JDK still is
-                    test.jvmArgs(
-                        "--add-exports=java.base/org.elasticsearch.entitlement.bridge=ALL-UNNAMED,"
-                            + modulesContainingEntitlementInstrumentation
-                    );
-                }
+                String modulesContainingEntitlementInstrumentation = "java.logging,java.net.http,java.naming,jdk.net";
+                test.getInputs().files(bridgeFiles).optional(true);
+                // Tests may not be modular, but the JDK still is
+                test.jvmArgs(
+                    "--add-exports=java.base/org.elasticsearch.entitlement.bridge=ALL-UNNAMED,"
+                        + modulesContainingEntitlementInstrumentation
+                );
             });
     }