[fixes #2327] mostly trivial: Added this. for field access and unified code gen of build() methods for @Builder.

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

@@ -45,7 +45,7 @@ public @Builder class BuilderDefaultsWarnings {
       default :
           items = java.util.Collections.unmodifiableList(new java.util.ArrayList<String>(this.items));
       }
-      return new BuilderDefaultsWarnings(x, z, items);
+      return new BuilderDefaultsWarnings(this.x, this.z, items);
     }
     public @java.lang.Override @java.lang.SuppressWarnings("all") java.lang.String toString() {
       return (((((("BuilderDefaultsWarnings.BuilderDefaultsWarningsBuilder(x=" + this.x) + ", z=") + this.z) + ", items=") + this.items) + ")");