Use env variable on setting of kafka producer

[Themesaul]

I am trying to put the list of brokers and topics from environment variable with "$env [KAFKA_BROKER_URLS]" and when I run it I get the following error:

Failed to create engine: unable to create stage 'github.com/project-flogo/contrib/activity/kafka' : BrokerUrl [=$env[KAFKA_BROKER_URLS]] format invalid for reason: [BrokerUrl must be composed of sections like "host:port"]

[skothari-tibco]

How does your Broker_URLS look like?