docs: private Set<ExecutableElement> abstractMethods(TypeElement typeElement) {
      Set<ExecutableElement> methods =
          getLocalAndInheritedMethods(
              typeElement, processingEnv.getTypeUtils(), processingEnv.getElementUtils());
      ImmutableSet.Builder<ExecutableElement> abstractMethods = ImmutableSet.builder();
      for (ExecutableElement method : methods) {
        if (method.getModifiers().contains(Modifier.ABSTRACT)) {
          abstractMethods.add(method);
        }
      }
      return abstractMethods.build();
    }