Advertise lambdas as arguments to then / runRemotely

src/main/java/org/jvnet/hudson/test/RealJenkinsRule.java

@@ -745,9 +745,8 @@ public String[] getTruststoreJavaOptions() {
     /**
      * One step to run.
      * <p>Since this thunk will be sent to a different JVM, it must be serializable.
-     * The test class will certainly not be serializable, so you cannot use an anonymous inner class,
-     * and regular lambdas also risk accidentally capturing non-serializable objects from scope.
-     * The friendliest idiom is a static method reference:
+     * The test class will certainly not be serializable, so you cannot use an anonymous inner class.
+     * One idiom is a static method reference:
      * <pre>
      * &#64;Test public void stuff() throws Throwable {
      *     rr.then(YourTest::_stuff);
@@ -759,6 +758,15 @@ public String[] getTruststoreJavaOptions() {
      * If you need to pass and/or return values, you can still use a static method reference:
      * try {@link #runRemotely(Step2)} or {@link #runRemotely(StepWithReturnAndOneArg, Serializable)} etc.
      * (using {@link XStreamSerializable} as needed).
+     * <p>
+     * Alternately, you could use a lambda (taking care not to capture non-serializable objects from scope):
+     * <pre>
+     * &#64;Test public void stuff() throws Throwable {
+     *     rr.then(r -> {
+     *         // as needed
+     *     });
+     * }
+     * </pre>
      */
     @FunctionalInterface
     public interface Step extends Serializable {

src/test/java/org/jvnet/hudson/test/RealJenkinsRuleTest.java

@@ -398,11 +398,19 @@ public boolean perform(AbstractBuild<?, ?> build, Launcher launcher, BuildListen
         // Neither ParametersDefinitionProperty nor ParametersAction could be passed directly.
         // (In this case, ParameterDefinition and ParameterValue could have been used raw.
         // But even List<ParameterValue> cannot be typed here, only e.g. ArrayList<ParameterValue>.)
-        var a = rr.runRemotely(RealJenkinsRuleTest::_xStreamSerializable, XStreamSerializable.of(new ParametersDefinitionProperty(new StringParameterDefinition("X", "dflt"))));
-        assertThat(a.object().getAllParameters(), hasSize(1));
-    }
-
-    private static XStreamSerializable<ParametersAction> _xStreamSerializable(JenkinsRule r, XStreamSerializable<JobProperty<? super FreeStyleProject>> prop) throws Throwable {
+        var prop = XStreamSerializable.of(new ParametersDefinitionProperty(new StringParameterDefinition("X", "dflt")));
+        // Static method handle idiom:
+        assertThat(rr.runRemotely(RealJenkinsRuleTest::_xStreamSerializable, prop).object().getAllParameters(), hasSize(1));
+        // Lambda idiom:
+        assertThat(rr.runRemotely(r -> {
+            var p = r.createFreeStyleProject();
+            p.addProperty(prop.object());
+            var b = r.buildAndAssertSuccess(p);
+            return XStreamSerializable.of(b.getAction(ParametersAction.class));
+        }).object().getAllParameters(), hasSize(1));
+    }
+
+    private static XStreamSerializable<ParametersAction> _xStreamSerializable(JenkinsRule r, XStreamSerializable<? extends JobProperty<? super FreeStyleProject>> prop) throws Throwable {
         var p = r.createFreeStyleProject();
         p.addProperty(prop.object());
         var b = r.buildAndAssertSuccess(p);