import java.util.Set; @lombok.experimental.SuperBuilder class SuperBuilderSingularCustomized { @lombok.Singular private Set<String> foos; public static abstract class SuperBuilderSingularCustomizedBuilder<C extends SuperBuilderSingularCustomized, B extends SuperBuilderSingularCustomized.SuperBuilderSingularCustomizedBuilder<C, B>> { public B custom(final String value) { return self(); } }}