code: public com.google.protobuf.ByteString
        getHttpHeaderBytes() {
      java.lang.Object ref = httpHeader_;
      if (ref instanceof java.lang.String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (java.lang.String) ref);
        httpHeader_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
docs: <pre>
  Define the HTTP header name to use for the parameter. It is case
  insensitive.
  </pre>
  
  <code>string http_header = 2;</code>