Embedded Kafka always uses plaintext for communicating to brokers

Hi,

I posted this issue on stack overflow creating an embedded SASL_SSL enabled kafka. It appears that right now, the Embedded kafka is designed to only ever use the plaintext protocol for it’s broker communication. This might not always be the case, depending on how people might want to set up their test environment. It can be fixed by something like below:

if (this.kafkaPorts[i] == 0) {
      this.kafkaPorts[i] = TestUtils.boundPort(server, SecurityProperties.forName(this.brokerProperties.getOrDefault("security.protocol", SecurityProtocol.PLAINTEXT).toString()); // or whatever property provides security protocol I should be using to communicate.
}

as opposed to

if (this.kafkaPorts[i] == 0) {
    this.kafkaPorts[i] = TestUtils.boundPort(server, SecurityProtocol.PLAINTEXT);
}

in EmbeddedKafkaBroker.java