code: public Optional<SshKey> getOptionalSshKey(Integer keyId) {
          try {
              return (Optional.ofNullable(getSshKey(keyId)));
          } catch (GitLabApiException glae) {
              return (GitLabApi.createOptionalFromException(glae));
          }
      }
docs: Get a single SSH Key as an Optional instance.
  
  <pre><code>GitLab Endpoint: GET /user/keys/:key_id</code></pre>
  
  @param keyId the ID of the SSH key
  @return an SshKey as an Optional instance holding the info on the SSH key specified by keyId