title: Writing JSON schema to detect objects with duplicate names
body: <p>According to the following post;</p>
  
  <p><a href="https://stackoverflow.com/questions/21832701/does-json-syntax-allow-duplicate-keys-in-an-object?lq=1">Does JSON syntax allow duplicate keys in an object?</a></p>
  
  <p>Keys with the same name in JSON are valid, but most parsers will override the value with the last value it finds. Is there anyway in a json schema to detect duplicate names and throw an error? I want all json keys to have unique names in an object.</p>