• Version of Ruby: 2.6.0
• Version of Kafka: 1.1.1
• Version of ruby-kafka: 1.0.0

Steps to reproduce

kafka = Kafka.new( seed_brokers: seed_brokers, ssl_client_cert: File.read(cert_path), ssl_client_cert_key: File.read(cert_key_path), ssl_verify_hostname: false ) kafka.topics 

Expected outcome

I expected the verify_hostname attr of the ssl_context to be set to false and passed to the OpenSSL gem with that value so that hostname is not verified and I can successfully connect to the broker.

Actual outcome

The verify_hostname attribute is ignored unless I explicitly pass in a ca_cert* parameter. Since it is defaulted to true in the OpenSSL gem, I'm getting these SSL errors:

ERROR: OpenSSL::SSL::SSLError - SSL_connect returned=1 errno=0 state=error: certificate verify failed (unspecified certificate verification error) 

I'm able to get around this by either downgraded to Ruby v2.3.3 (where that version of OpenSSL does not default verify_hostname) or by setting ssl_ca_certs_from_system: true in v2.6.0, which I don't need in my case since my client_cert is a combined cert. I can open up a PR to move the verify_hostname assignment out of this conditional but wanted to check if that was intentional and expected.