void detectParcelableCreator() {
    for (VariableElement v : ElementFilter.fieldsIn(element.getEnclosedElements())) {
      if (v.getSimpleName().contentEquals(Proto.PARCELABLE_CREATOR_FIELD)) {
        hasCreatorDefined = true;
        break;
      }
    }
  }
Means object hashcode is cached at some point. Either lazily (on first access)
or eagerly (during construction).
@see #isUseLazyhash()
@see #isUsePrehashed()
value-processor/src/org/immutables/value/processor/meta/ValueType.java