[issue #2221] simplified configuration for @Singular-generated plural form nullchecks.

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

@@ -13,7 +13,9 @@ import lombok.Singular;
     }
     public @java.lang.SuppressWarnings("all") BuilderSingularToBuilderWithNullWithSetterPrefix.BuilderSingularToBuilderWithNullWithSetterPrefixBuilder withElems(final java.util.Collection<? extends String> elems) {
       if ((elems == null))
-          throw new java.lang.NullPointerException("elems cannot be null");
+          {
+            throw new java.lang.NullPointerException("elems cannot be null");
+          }
       if ((this.elems == null))
           this.elems = new java.util.ArrayList<String>();
       this.elems.addAll(elems);