Not able to use jvm default cacerts trust store for hec https verification

[wangshu3000]

JRE default cacerts includes many publicly trusted ca cert.
I would like to use the default ca trust store provided by java.

But if the splunk.hec.ssl.validate.certs is set to true. There is a validation that the splunk.hec.ssl.trust.store.path also must be configured.
I can not unset the splunk.hec.ssl.trust.store.path parameter to use default cacert trust store.

The expected logic would be:
If splunk.hec.ssl.validate.certs is set to true, then:
    If splunk.hec.ssl.trust.store.path is configured, verify ssl using the trust store that specified
    If splunk.hec.ssl.trust.store.path is not configured or blank, verify ssl using cacert default trust store.
Else If splunk.hec.ssl.validate.certs is set to false, then:
    Skip all ssl verification

Please confirm if this makes sense, if it sounds good, i can raise a PR for it.
Thanks.