code: public void setAllowedHeaders(java.util.Collection<String> allowedHeaders) {
          if (allowedHeaders == null) {
              this.allowedHeaders = null;
              return;
          }
  
          this.allowedHeaders = new java.util.ArrayList<String>(allowedHeaders);
      }
docs: <p>
  Specifies which headers are allowed in a preflight <code>OPTIONS</code> request through the
  <code>Access-Control-Request-Headers</code> header. Each header name that is specified in
  <code>Access-Control-Request-Headers</code> must have a corresponding entry in the rule. Only the headers that
  were requested are sent back.
  </p>
  <p>
  This element can contain only one wildcard character (*).
  </p>
  
  @param allowedHeaders
  Specifies which headers are allowed in a preflight <code>OPTIONS</code> request through the
  <code>Access-Control-Request-Headers</code> header. Each header name that is specified in
  <code>Access-Control-Request-Headers</code> must have a corresponding entry in the rule. Only the headers
  that were requested are sent back. </p>
  <p>
  This element can contain only one wildcard character (*).