code: private static void setupRequestHeaders() {
      requestHeaders = new AsciiString[18];
      int i = 0;
      requestHeaders[i++] = AsciiString.of(":method");
      requestHeaders[i++] = AsciiString.of("POST");
      requestHeaders[i++] = AsciiString.of(":scheme");
      requestHeaders[i++] = AsciiString.of("http");
      requestHeaders[i++] = AsciiString.of(":path");
      requestHeaders[i++] = AsciiString.of("/google.pubsub.v2.PublisherService/CreateTopic");
      requestHeaders[i++] = AsciiString.of(":authority");
      requestHeaders[i++] = AsciiString.of("pubsub.googleapis.com");
      requestHeaders[i++] = AsciiString.of("te");
      requestHeaders[i++] = AsciiString.of("trailers");
      requestHeaders[i++] = AsciiString.of("grpc-timeout");
      requestHeaders[i++] = AsciiString.of("1S");
      requestHeaders[i++] = AsciiString.of("content-type");
      requestHeaders[i++] = AsciiString.of("application/grpc+proto");
      requestHeaders[i++] = AsciiString.of("grpc-encoding");
      requestHeaders[i++] = AsciiString.of("gzip");
      requestHeaders[i++] = AsciiString.of("authorization");
      requestHeaders[i] = AsciiString.of("Bearer y235.wef315yfh138vh31hv93hv8h3v");
    }
docs: Headers taken from the gRPC spec.