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

test/transform/resource/before/BuilderSingularMapsWithSetterPrefix.java

@@ -1,7 +1,6 @@
 //FORMAT: javaLangAsFQN = skip
 //FORMAT: generated = skip
 //FORMAT: finalParams = skip
-//CONF: lombok.singular.nullCollections = ignore
 import java.util.Map;
 import java.util.SortedMap;
 
@@ -11,6 +10,6 @@ import lombok.Singular;
 class BuilderSingularMapsWithSetterPrefix<K, V> {
 	@Singular private Map<K, V> women;
 	@Singular private SortedMap<K, ? extends Number> men;
-	@SuppressWarnings("all") @Singular("rawMap") private Map rawMap;
+	@SuppressWarnings("all") @Singular(value = "rawMap", ignoreNullCollections = true) private Map rawMap;
 	@Singular("stringMap") private Map<String, V> stringMap;
 }