title: Resolver to filter a non-scalar type in AppSync / Amplify
body: <p>We are using AWS Amplify. This is my type</p>
  
  <pre><code>type Package @model {
    id: ID!
    desc: String!
    company: Company! @connection
    servicetype: ServiceType! @connection
    price: Float!
    active: Boolean!
    createdAt: AWSDateTime
    updatedAt: AWSDateTime
  }
  </code></pre>
  
  <p>Amplify does not generate a filter option for listPackage to allow filtering on servicetype. My understanding is you need to add a custom query and resolver for this. I have added a query listPackageByServiceType but am confused on the resolver... cannot get it to work. </p>
  
  <p>Is there a similar example of code I can follow? I cannot get the filter option to work correctly.</p>