private void refreshValue() {
        try {
            refreshableValueHolder
                    .compareAndSet(refreshableValueHolder.get(), refreshCallable.call());
        } catch (AmazonServiceException ase) {
            // Preserve the original ASE
            throw ase;
        } catch (AmazonClientException ace) {
            // Preserve the original ACE
            throw ace;
        } catch (Exception e) {
            throw new AmazonClientException(e);
        }
    }
Invokes the callback to get a new value.
aws-java-sdk-sts/src/main/java/com/amazonaws/auth/RefreshableTask.java