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;
                }
            }
<code>optional string format = 4;</code>

@return The bytes for format.
turms-server-common/src/main/java/im/turms/server/common/access/client/dto/model/file/AudioFile.java