Disable Webhook TLS / Security?

I’m testing out some webhook on an unsecure server. However, I am getting a certificate validation error from the ES Nodes:

javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
	at sun.security.ssl.Alert.createSSLException(Alert.java:128) ~[?:?]
	at sun.security.ssl.TransportContext.fatal(TransportContext.java:321) ~[?:?]
	at sun.security.ssl.TransportContext.fatal(TransportContext.java:264) ~[?:?]
	at sun.security.ssl.TransportContext.fatal(TransportContext.java:259) ~[?:?]

I suppose this is expected but I don’t see anything in the docs on disabling TLS validation for webhooks?

Does anyone know how?