After adding throttling kafka plugin not working properly

[AkshayDubey29]

throttling config

<filter k8s_log.**>
@type throttle
group_key $.kubernetes.namespace_name
group_bucket_period_s 60
group_bucket_limit 6000
group_reset_rate_s 100

<match .k8s_log.>
@id copy_k8s_log
log_level trace
@type copy

@id kafka_buffered_k8s_log
reserve_data true
@log_level trace
@type kafka_buffered
brokers {brokers list}
default_topic fluent_data
output_include_tag true
#output_include_time true
required_acks 1
kafka_agg_max_bytes 10000000
kafka_agg_max_messages 1000000
max_send_limit_bytes 9000000000 #to avoid MessageSizeTooLarge
get_kafka_client_log true
#
#@type memory
#flush_mode immediate
#flush_thread_count 20
#chunk_limit_size 8MB
#total_limit_size 64MB
#overflow_action drop_oldest_chunk
#


@id out_prometheus_k8s_log
@type prometheus

name fluentd_output_status_num_records_total
type counter
desc The total number of outgoing records

tag ${tag}
hostname ${hostname}

failed to flush the buffer. retry_time=2 next_retry_seconds=2018-09-03 07:18:49 +0000 chunk="574f2567d5ab677a1bd50654f855d45d" error_class=ArgumentError error="wrong number of arguments (given 6, expected 0)"
2018-09-03 07:18:49 +0000 [warn]: #0 suppressed same stacktrace
2018-09-03 07:18:50 +0000 [info]: #0 following tail of /applog/container/logs/json/splunk_2018-09-03.0718.log
2018-09-03 07:18:50 +0000 [trace]: #0 [kafka_buffered_k8s_log] enqueueing all chunks in buffer instance=47336657585960
2018-09-03 07:18:53 +0000 [warn]: #0 [kafka_buffered_fluent_logs] Send exception occurred: wrong number of arguments (given 6, expected 0)
2018-09-03 07:18:53 +0000 [warn]: #0 [kafka_buffered_fluent_logs] Exception Backtrace : /usr/lib/ruby/gems/2.4.0/gems/ruby-kafka-0.7.0/lib/kafka/pending_message.rb:7:in initialize' /usr/lib/ruby/gems/2.4.0/gems/fluent-plugin-kafka-0.6.6/lib/fluent/plugin/kafka_producer_ext.rb:16:in new'
/usr/lib/ruby/gems/2.4.0/gems/fluent-plugin-kafka-0.6.6/lib/fluent/plugin/kafka_producer_ext.rb:16:in produce2' /usr/lib/ruby/gems/2.4.0/gems/fluent-plugin-kafka-0.6.6/lib/fluent/plugin/out_kafka_buffered.rb:322:in block in write'
/usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/event.rb:323:in each' /usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/event.rb:323:in block in each'
/usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/plugin/buffer/memory_chunk.rb:80:in open' /usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/plugin/buffer/memory_chunk.rb:80:in open'
/usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/event.rb:322:in each' /usr/lib/ruby/gems/2.4.0/gems/fluent-plugin-kafka-0.6.6/lib/fluent/plugin/out_kafka_buffered.rb:284:in write'
/usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/compat/output.rb:131:in write' /usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/plugin/output.rb:1094:in try_flush'
/usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/plugin/output.rb:1319:in flush_thread_run' /usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/plugin/output.rb:439:in block (2 levels) in start'
/usr/lib/ruby/gems/2.4.0/gems/fluentd-1.1.0/lib/fluent/plugin_helper/thread.rb:78:in `block in thread_create'