@Override
    public String toString(boolean verbose) {
        // Use the same format as `Struct.toString()`
        StringBuilder bld = new StringBuilder();
        bld.append("{acks=").append(acks)
                .append(",timeout=").append(timeout);

        if (verbose)
            bld.append(",partitionSizes=").append(Utils.mkString(partitionSizes(), "[", "]", "=", ","));
        else
            bld.append(",numPartitions=").append(partitionSizes().size());

        bld.append("}");
        return bld.toString();
    }
@return data or IllegalStateException if the data is removed (to prevent unnecessary memory retention).
clients/src/main/java/org/apache/kafka/common/requests/ProduceRequest.java