@Nullable
  public Object signingSignature() {
    try {
      Field signaturesField = piClass.getField("signatures");
      Object[] signatures = (Object[]) signaturesField.get(piInstance);
      if (signatures == null || signatures.length == 0 || signatures[0] == null) {
        return null;
      }
      return signatures[0];
    } catch (NoSuchFieldException | IllegalAccessException e) {
      e.printStackTrace();
    }
    return null;
  }
@return the signing signature for the app
src/main/java/com/google/maps/android/PackageInfo.java