code: public static void addMetadata(final HttpURLConnection request, final Map<String, String> metadata,
              final OperationContext opContext) {
          if (metadata != null) {
              for (final Entry<String, String> entry : metadata.entrySet()) {
                  addMetadata(request, entry.getKey(), entry.getValue(), opContext);
              }
          }
      }
docs: Adds the metadata.
  
  @param request
  The request.
  @param metadata
  The metadata.