Webrev: http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8178404/webrev.00/index.html
--suggest-providers should suggest providers from any observable modules rather than the resolved modules. This patch also improves the output and fixes JDK-8178405 and JDK-8178327. --add-modules has no effect to the suggested providers when —suggest-providers is specified. Mandy