code: public CORSConfigBuilder withExposedHeaders(String... headerNames) {
          Mutils.notNull("headerNames", headerNames);
          return withExposedHeaders(asList(headerNames));
      }
docs: <p>Specifies which headers (aside from "simple" headers) are allowed to be accessed by JavaScript in responses.</p>
  <p>The "simple" headers are: <code>Cache-Control</code>, <code>Content-Language</code>,
  <code>Content-Type</code>, <code>Expires</code>, <code>Last-Modified</code>, <code>Pragma</code>
  (so you do not need to specify these values).</p>
  @param headerNames The names of headers to allow, for example <code>Content-Type</code>
  @return This builder