I sent a small message at 09:21:47, and I see below entries in LogStash logs. I sent a big message at 09:23:04, and there is nothing in the logs, only "Flushing buffer at interval".
{:timestamp=>"2016-03-02T09:21:47.740000-0600", :message=>"Flushing buffer at interval", :instance=>"#<LogStash::Outputs::ElasticSearch::Buffer:0x48de003c @operations_mutex=#Mutex:0x4619e757, @max_size=500, @operations_lock=#<Java::JavaUtilConcurrentLocks::Re
{:timestamp=>"2016-03-02T09:21:47.795000-0600", :message=>"Flushing buffer at interval", :instance=>"#<LogStash::Outputs::ElasticSearch::Buffer:0x225c556a @operations_mutex=#Mutex:0x2c9bbf51, @max_size=500, @operations_lock=#<Java::JavaUtilConcurrentLocks::Re
{:timestamp=>"2016-03-02T09:21:47.795000-0600", :message=>"Flushing buffer at interval", :instance=>"#<LogStash::Outputs::ElasticSearch::Buffer:0xc6c93c1 @operations_mutex=#Mutex:0x2ab6c3c, @max_size=500, @operations_lock=#<Java::JavaUtilConcurrentLocks::Reen
{:timestamp=>"2016-03-02T09:21:47.836000-0600", :message=>"filter received", :event=>{"LogMessage"=>{"Header"=>{"Source"=>"BPM", "CreatedDateTime"=>"2016-03-01T19:03:31.032Z", "MessageType"=>"Event", "MessageName"=>"CustomerCaseGraphDataService", "MessageVersio
{:timestamp=>"2016-03-02T09:21:47.841000-0600", :message=>"Date filter: received event", :type=>nil, :level=>:debug, :file=>"/logstash-2.2.2/vendor/bundle/jruby/1.9/gems/logstash-filter-date-2.1.2/lib/logstash/filters/date.rb", :line=>"229", :method=>"filter"}
{:timestamp=>"2016-03-02T09:21:47.842000-0600", :message=>"Date filter looking for field", :type=>nil, :field=>"[LogMessage][Header][CreatedDateTime]", :level=>:debug, :file=>"/logstash-2.2.2/vendor/bundle/jruby/1.9/gems/logstash-filter-date-2.1.2/lib/logstash/filters/date.rb", :line=>"232", :method=>"filter"}
{:timestamp=>"2016-03-01T19:03:31.032Z", :message=>"Date parsing done", :value=>"2016-03-01T19:03:31.032Z", :level=>:debug, :file=>"/logstash-2.2.2/vendor/bundle/jruby/1.9/gems/logstash-filter-date-2.1.2/lib/logstash/filters/date.rb", :line=>"266", :method=>"filter"}
{:timestamp=>"2016-03-02T09:21:47.844000-0600", :message=>"filters/LogStash::Filters::Mutate: removing field", :field=>"host", :level=>:debug, :file=>"/logstash-2.2.2/vendor/bundle/jruby/1.9/gems/logstash-core-2.2.2-java/lib/logstash/filters/base.rb", :line=>"175", :method=>"filter_matched"}
{:timestamp=>"2016-03-02T09:21:47.845000-0600", :message=>"filters/LogStash::Filters::Mutate: removing field", :field=>"headers", :level=>:debug, :file=>"/logstash-2.2.2/vendor/bundle/jruby/1.9/gems/logstash-core-2.2.2-java/lib/logstash/filters/base.rb", :line=>"175", :method=>"filter_matched"}
{:timestamp=>"2016-03-02T09:21:47.846000-0600", :message=>"output received", :event=>{"LogMessage"=>{"Header"=>{"Source"=>"BPM", "CreatedDateTime"=>"2016-03-01T19:03:31.032Z", "MessageType"=>"Event", "MessageName"=>"CustomerCaseGraphDataService", "MessageVersio
{:timestamp=>"2016-03-02T09:21:48.140000-0600", :message=>"Flushing buffer at interval", :instance=>"#<LogStash::Outputs::ElasticSearch::Buffer:0x7f1e40ab @operations_mutex=#Mutex:0x71d9a138, @max_size=500, @operations_lock=#<Java::JavaUtilConcurrentLocks::Re
{:timestamp=>"2016-03-02T09:21:48.202000-0600", :message=>"Flushing buffer at interval", :instance=>"#<LogStash::Outputs::ElasticSearch::Buffer:0x31332f @operations_mutex=#Mutex:0xef6dd59, @max_size=500, @operations_lock=#<Java::JavaUtilConcurrentLocks::Reent
{:timestamp=>"2016-03-02T09:21:48.278000-0600", :message=>"Flushing buffer at interval", :instance=>"#<LogStash::Outputs::ElasticSearch::Buffer:0x4fde0221 @operations_mutex=#Mutex:0x4119e5aa, @max_size=500, @operations_lock=#<Java::JavaUtilConcurrentLocks::Re