[trivial] improving consistency between javac vs. ecj output

wasn't worth an issue on the tracker: javac and ecj handlers for static constructors would differ; ecjs would specify the return type and constructor invocation using fully qualified types, whereas the handler for javac did not.

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

@@ -0,0 +1,13 @@
+class ConstructorInner {
+  static @lombok.AllArgsConstructor(staticName = "of") class Inner {
+    private @java.lang.SuppressWarnings("all") Inner() {
+      super();
+    }
+    public static @java.lang.SuppressWarnings("all") ConstructorInner.Inner of() {
+      return new ConstructorInner.Inner();
+    }
+  }
+  ConstructorInner() {
+    super();
+  }
+}