Javadocs.
Added CancellationTokenInternal, to allow the public token to be unpacked to the backing internal token
Added the cancellation token to ConsumerOperationParameters so that it is shipped around with all the other parameters.
Changed ToolingImplementationLoader and Distribution to use the internal BuildCancellationToken type instead of the public type.
Removed CancellationToken from ConsumerConnection methods - it's packaged in the parameters instead.
Removed CancellationToken from ModelProducer methods - it's packaged in the parameters instead.
Changed some usages of public CancellationToken to internal BuildCancellationToken.
Removed the callback methods from CancellationToken.
Moved some Gradle version specific knowledge from several tests up to ToolingApiSpecification.