[fixes #3463] Support argument widening for extension methods

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

@@ -0,0 +1,18 @@
+import lombok.experimental.ExtensionMethod;
+@ExtensionMethod({ExtensionMethodWidening.Extensions.class}) class ExtensionMethodWidening {
+  static class Extensions {
+    Extensions() {
+      super();
+    }
+    public static String widening(String string, long a) {
+      return ((string + " ") + a);
+    }
+  }
+  ExtensionMethodWidening() {
+    super();
+  }
+  public void test() {
+    String string = "test";
+    ExtensionMethodWidening.Extensions.widening(string, 1);
+  }
+}