/**
 * Returns the remote issue with the given id or <code>null</code> if it wasn't found.
 */
@CheckForNull
public JiraIssue getIssue(final String id) throws IOException {
    try {

        Issue issue = issueCache.get(id, new Callable<Issue>() {
            public Issue call() throws Exception {
                JiraSession session = getSession();
                Issue issue = null;
                if (session != null) {
                    issue = session.getIssue(id);
                }
                return issue;
            }
        });

        if (issue == null) {
            return null;
        }

        return new JiraIssue(issue);
    } catch (ExecutionException e) {
        throw new IOException(e);
    }
}

V get(K key, Callable<? extends V> valueLoader) throws ExecutionException;