code: 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);
          }
      }
docs: Invokes the callback to get a new value.