Verbatim advanced configuration file contents using the Erlang syntax. This is also known as the advanced.config file or the old config format.
configItems is preferred whenever possible. However, nested data structures can only be expressed properly using the config option.
The contents of this option will be merged into the configItems by RabbitMQ at runtime to form the final configuration.
See the second table on https://www.rabbitmq.com/configure.html#config-items For the distinct formats, see https://www.rabbitmq.com/configure.html#config-file-formats.