Order of log entries not maintained

When we log multiple events during the same millisecond the order that they're logged isn't maintained when viewing those events in Splunk. Note that we're using a batch_size_count (which should be batchSizeCount, but that's a different issue) of 1 since we want to increase the chance that all events get persisted to Splunk.

logback.xml exhibiting the issue:

<configuration>
<appender name="splunk" class="com.splunk.logging.HttpEventCollectorLogbackAppender">
<url>${SPLUNK_URL}</url>
<token>${SPLUNK_TOKEN}</token>
<index>${SPLUNK_INDEX}</index>
<host>${SPLUNK_HOST}</host>
<connectTimeout>2000</connectTimeout>
<writeTimeout>1000</writeTimeout>
<batch_size_count>1</batch_size_count>
<includeMDC>false</includeMDC>
<includeThreadName>false</includeThreadName>

<layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
<jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
<prettyPrint>false</prettyPrint>
</jsonFormatter>

<includeTimestamp>false</includeTimestamp>
<includeLevel>false</includeLevel>
<includeLoggerName>false</includeLoggerName>
<includeMDC>false</includeMDC>
<includeThreadName>false</includeThreadName>
<includeContextName>false</includeContextName>
</layout>
</appender>

<root level="info">
<appender-ref ref="splunk" />
</root>
</configuration>
`

Start with the logback.xml configuration shown, especially the Splunk HttpEventCollectorLogbackAppender and batch_size_count setting. Reproduce multiple events logged within the same millisecond and inspect their order in Splunk. Done means the persisted events retain their logging order without removing the batch_size_count=1 configuration.