[android] Remove UnknownLayer

platform/android/MapboxGLAndroidSDK/src/main/java/com/mapbox/mapboxsdk/style/layers/UnknownLayer.java

@@ -1,27 +0,0 @@
-package com.mapbox.mapboxsdk.style.layers;
-
-import android.support.annotation.Keep;
-import android.support.annotation.UiThread;
-
-/**
- * An unknown type of layer
- */
-@UiThread
-@Keep
-public class UnknownLayer extends Layer {
-
-  /**
-   * Creates a UnknownLayer.
-   *
-   * @param nativePtr pointer used by core
-   */
-  UnknownLayer(long nativePtr) {
-    super(nativePtr);
-  }
-
-  protected native void initialize();
-
-  @Override
-  protected native void finalize() throws Throwable;
-
-}