public com.google.protobuf.ByteString
          getFormatBytes() {
        java.lang.Object ref = format_;
        if (ref instanceof String) {
          com.google.protobuf.ByteString b =
              com.google.protobuf.ByteString.copyFromUtf8(
                  (java.lang.String) ref);
          format_ = b;
          return b;
        } else {
          return (com.google.protobuf.ByteString) ref;
        }
      }
<pre>
avi, jpg, youtube, cnbc, audio/mpeg formats ...
</pre>

<code>string format = 5;</code>
@return The bytes for format.
benchmark/src/main/java/com/alibaba/fastjson2/benchmark/protobuf/MediaContentHolder.java