title: Cannot parse json objects with GSON when setting minifyEnabled is true
body: <p>When I use</p>
  <pre><code>buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
      }
  </code></pre>
  <p>everything works perfectly.</p>
  <p>But if change to</p>
  <pre><code>buildTypes {
          release {
              minifyEnabled true
              useProguard true
              shrinkResources true
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
      }
  </code></pre>
  <p>I get a parsing error.</p>
  <p>My classes for parse:</p>
  <pre><code>data class SearchItem(
      @SerializedName(&quot;position&quot;) val position: Long,
      @SerializedName(&quot;user&quot;) val user: String?
  ) {
      fun getId(): Long {
          return 0L
      }
  }
  
  data class SearchResponse(
      @SerializedName(&quot;list&quot;) val list: List&lt;SearchItem&gt;,
      @SerializedName(&quot;has_more&quot;) val has_more: Boolean,
      @SerializedName(&quot;rank_token&quot;) val rank_token: String,
      @SerializedName(&quot;status&quot;) val status: String
  )
  </code></pre>
  <p>Here I use gson:</p>
  <pre><code>val searchResponse = Gson().fromJson(jsonObject.toString(), SearchResponse::class.java)
  </code></pre>
  <p>In <code>proguard-rules.pro</code> I have one non-comment line <code>-keepattributes *Annotation*</code></p>
  <p>I would be grateful for any help!</p>
  <p><strong>EDIT</strong>
  Error log:</p>
  <pre><code>E/AndroidRuntime: FATAL EXCEPTION: k.c0 Dispatcher
      Process: PID: 31392
      java.lang.NullPointerException: throw with null exception
          at h.a.a.j.a.a.a(:2)
          at k.l0.g.e$a.run(:6)
          at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
          at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
          at java.lang.Thread.run(Thread.java:764)
  </code></pre>
  <p>This happens only with .apk installation. If I run the app from Android Studio all is fine.</p>