[fixes #3225] Handle ambiguous extension methods

test/transform/resource/after-ecj/ExtensionMethodAmbiguousFunctional.java

@@ -0,0 +1,20 @@
+import java.util.function.Consumer;
+import java.util.function.Function;
+import lombok.experimental.ExtensionMethod;
+@ExtensionMethod({ExtensionMethodAmbiguousFunctional.Extensions.class}) class ExtensionMethodAmbiguousFunctional {
+  static class Extensions {
+    Extensions() {
+      super();
+    }
+    public static <T, R>void ambiguous(T t, Function<T, R> function) {
+    }
+    public static <T>void ambiguous(T t, Consumer<T> function) {
+    }
+  }
+  ExtensionMethodAmbiguousFunctional() {
+    super();
+  }
+  public void test() {
+    "".ambiguous(System.out::println);
+  }
+}