Java 27 and 26: runnable demos and captured output for every JEP, plus version lanes

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01B38FGKKam5SCGgwgduVAh3

lanes/src/MockitoProbe.java

@@ -0,0 +1,15 @@
+import org.mockito.Mockito;
+
+/**
+ * Creates one mock and stubs one call: the smallest thing that makes Mockito ask ByteBuddy to read and write class files.
+ * Run by scripts/upgrade.sh against two Mockito versions on JDK 21 and 25. Explained in docs/15-build-files.md.
+ */
+public class MockitoProbe {
+    interface Greeter { String greet(String name); }
+
+    public static void main(String[] args) {
+        Greeter g = Mockito.mock(Greeter.class);
+        Mockito.when(g.greet("x")).thenReturn("hi");
+        System.out.println("mock says " + g.greet("x"));
+    }
+}