@Lazy
  protected Strategy getReflectionStrategy() {
    for (Strategy strategy : getStrategies()) {
      if (strategy.isAttributeBuilder()) {
        return strategy;
      }
    }

    throw new AssertionError("isAttributeBuilder flip-flopped from true to false.");
  }
Reflects over the returnType and generates strings for the {@link AttributeBuilderDescriptor}
value-processor/src/org/immutables/value/processor/meta/AttributeBuilderReflection.java