0.original-state-structure.js

// Originally, it was like this
{
  resources: {
     books: {
       
       // This shit is secret, and should not be exposed to the users.
       __internalInfoAboutBooks: {},

       resources: {
         24: { ... },
         50: { ... }
       }
     }
  }
}

1.new-state-structure.js

// Now, the metadata is stored in a separate object that is never exposed to the user
{
  resources: {
     books: {
       24: { ... },
       50: { ... }
     }
  }
}

// here is that separate object...
{
  resources: {
    books: {
      __internalInfoAboutBooks: {}
    }
  }
}