The RabbitMQ Connector has a Maven dependency under MPL 1.1.
The ASF legal FAQ (https://www.apache.org/legal/resolved) classifies that as "may be included in binary form within an Apache product if the inclusion is appropriately labeled".
Because we neither include sources nor binaries (but only define a Maven dependency) it is probably not relevant to Flink. But to be on the safe side for the project and users, we should add a notice as blow to the docs and the project:
# License of the Rabbit MQ Connector
Flink's RabbitMQ connector defines a Maven dependency on the
"RabbitMQ AMQP Java Client", licensed under the
Mozilla Public License v1.1 (MPL 1.1).
Flink itself neither reuses source code from the "RabbitMQ AMQP Java Client"
nor packages binaries from the "RabbitMQ AMQP Java Client".
Users that create and publish derivative work based on Flink's
RabbitMQ connector (thereby re-distributing the "RabbitMQ AMQP Java Client")
must be aware that this may be subject to conditions declared
in the Mozilla Public License v1.1 (MPL 1.1).