public java.lang.String getFormat() {
                java.lang.Object ref = format_;
                if (!(ref instanceof java.lang.String)) {
                    com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
                    java.lang.String s = bs.toStringUtf8();
                    format_ = s;
                    return s;
                } else {
                    return (java.lang.String) ref;
                }
            }
<code>optional string format = 4;</code>

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