Streaming Expressions should have better support for basic auth

I'm creating a StreamFactory object like the following code:

new StreamFactory().withDefaultZkHost(solrConfig.getConnectString())
                .withFunctionName("gatherNodes", GatherNodesStream.class);

However once I create the StreamFactory there is no way provided to set the CloudSolrClient object which can be used to set Basic Auth headers.

In StreamContext object there is a way to set the SolrClientCache object which keep reference to all the CloudSolrClient where I can set a reference to HttpClient which sets the Basic Auth header. However the problem is, inside the SolrClientCache there is no way to set your own version of CloudSolrClient with BasicAuth enabled.

I think we should expose method in StreamContext where I can specify basic-auth enabled CloudSolrClient to use.