[fixes #2682] Fix NPE, always add Javadoc return statement

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

@@ -7,6 +7,9 @@ public class JacksonizedSuperBuilderSimple {
       }
       protected abstract @java.lang.SuppressWarnings("all") B self();
       public abstract @java.lang.SuppressWarnings("all") C build();
+      /**
+       * @return {@code this}.
+       */
       public @java.lang.SuppressWarnings("all") B field1(final int field1) {
         this.field1 = field1;
         return self();