code: public static void convertActivityToTranslucent(Activity activity) {
          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
              convertActivityToTranslucentAfterL(activity);
          } else {
              convertActivityToTranslucentBeforeL(activity);
          }
      }
docs: Convert a translucent themed Activity
  {@link android.R.attr#windowIsTranslucent} back from opaque to
  translucent following a call to
  {@link #convertActivityFromTranslucent(android.app.Activity)} .
  <p>
  Calling this allows the Activity behind this one to be seen again. Once
  all such Activities have been redrawn
  <p>
  This call has no effect on non-translucent activities or on activities
  with the {@link android.R.attr#windowIsFloating} attribute.