Throwables.getCauseAsOptional

[RamAnvesh]

Throwables currently has

public static <X extends Throwable> X getCauseAs(Throwable throwable, Class<X> 
    expectedCauseType);

Can we add

public static Optional<X> getCauseAsOptional(Throwable throwable, Class<X> expectedCauseType){
    if(expectedCauseType.isInstance(throwable.getCause())){
      return Optional.of(expectedCauseType.cast(throwable.getCause()););
    } else {
      return Optional.empty();
    }
}

This enables clean conditional exception handling which can replace code this:

catch (ExecutionException e) {
    if ((e.getCause() instanceof AuthException)) {
        AuthException exception = (AuthException) e.getCause();
        if (exception.getCode().equals(AuthException.Code.USER_NOT_FOUND)) {
          // ignore the exception
        } else {
          throw e;
        }
      } else {
        throw e;
      }
}

with code like this:

catch (ExecutionException e) {
    getCauseAsOptional(e, AuthException.class)
        .map(authExp -> authExp.getCode())
        .filter(AuthException.Code.USER_NOT_FOUND::equals)
        .orElseThrow(() -> e);
}

The existing getCauseAs can be refactored to call this method internally.

[original-codematrix]

Can this be implemented?