With the kernel this isn't a problem for most Sakai developers and is very unlikely get fixed for 2.5.x

In my example I was writing my pom.xml file and then generating the eclipse files with "mvn eclipse:eclipse"

The project in question had a dependency on sakai-site-api but when I try and use SiteService.getSites() I get an error similar to:

/home/buckett/sakai/hierarchy/sakai-hierarchy-neighbourhood/src/java/org/sakaiproject/portal/HierarchyNeighbourhoodImpl.java:[29,7] cannot access org.sakaiproject.javax.PagingPosition
class file for org.sakaiproject.javax.PagingPosition not found
public class HierarchyNeighbourhoodImpl implements SiteNeighbourhoodService

which is because PagingPosition is in sakai-util-api.

I wasn't suggesting that APIs shouldn't depend on each other.

As I see it the bug is that although maven has transitive dependencies the correct APIs aren't being propogated to the project using the sakai-site-api.

Is this an Eclipse/build difficulty, or are you suggesting that site should not expose classes from authz/entity in its API ?

There are cases elsewhere in the code where it's assumed for example that the site groups implementation uses authz (e.g. passing a list of site group references to an authz API call).

You also need sakai-util-api.
In Eclipse it allows you to use the site API without having sakai-util-api but you can't use methods that require the util API (SiteService.getSites()).