Basic Auth for Solr Streaming Expressions

[sandeep mukherjee]

Hello everyone,
I trying to find the documentation for Basic Auth plugin for Solr Streaming 
expressions. But I'm not able to find it in the documentation anywhere. Could 
you please point me in right direction of how to enable Basic auth for Solr 
Streams?
I'm creating StreamFactory as follows: I wonder how and where can I specify 
Basic Auth username and password
@Bean
public StreamFactory streamFactory() {
    SolrConfig solrConfig = ConfigManager.getNamedConfig("solr", 
SolrConfig.class);

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