title: Declare type of a struct field by type of another struct field
body: <p>Here is *s3.GetObjectOutput struct:</p>
  
  <pre><code>type GetObjectOutput struct {
      ...
      Metadata map[string]*string
      ...
  }
  </code></pre>
  
  <p>I want to declare my struct with a struct field has type of Metadata field in GetObjectOutput struct like this</p>
  
  <pre><code>type MyObject struct {
      Metadata *s3.GetObjectOutput.Metadata
      ...
  }
  </code></pre>
  
  <p>But it was not correct. How do I declare a struct with a field has type of another struct's field instead of explicitly write down:</p>
  
  <pre><code>type MyObject struct {
      Metadata map[string]*string
      ...
  }
  </code></pre>