`MetadataManager.contactPoints` may be Misused.

Some usage of `getContactPoints()` (for `MetadataManager.contactPoints`) may be wrong. They may want to use `metadata.getNodes()` instead, like this one.

`MetadataManager.contactPoints` are hard-coded initial config of nodes, not including any nodes added in runtime. Consider changing it to `public final ImmutableSet<EndPoint>` instead.

More investigation needed.