docs: static ImmutableSet<ExecutableElement> propertyMethodsIn(Set<ExecutableElement> abstractMethods) {
      ImmutableSet.Builder<ExecutableElement> properties = ImmutableSet.builder();
      for (ExecutableElement method : abstractMethods) {
        if (method.getParameters().isEmpty()
            && method.getReturnType().getKind() != TypeKind.VOID
            && objectMethodToOverride(method) == ObjectMethod.NONE) {
          properties.add(method);
        }
      }
      return properties.build();
    }