When adding drools-api as a dependency of another maven project, it will try to download the drools-api jar from the jboss maven repo, but then fail to download its parent somehow.
If you first build drools locally, it can then find the parent pom in the repository succesfully.

[INFO] snapshot org.drools:drools-api:5.2.0.SNAPSHOT: checking for updates from jboss-public-repository-group
Downloading: https://repository.jboss.org/nexus/content/groups/public//org/drools/drools-api/5.2.0.SNAPSHOT/drools-api-5.2.0.20101123.060233-380.pom
6K downloaded (drools-api-5.2.0.20101123.060233-380.pom)
[INFO] snapshot org.drools:drools:5.2.0.SNAPSHOT: checking for updates from jboss-public-repository-group
Downloading: https://repository.jboss.org/nexus/content/groups/public//org/drools/drools/5.2.0.SNAPSHOT/drools-5.2.0.SNAPSHOT.pom
[INFO] Unable to find resource 'org.drools:drools:pom:5.2.0.SNAPSHOT' in repository jboss-public-repository-group (https://repository.jboss.org/nexus/content/groups/public/)
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error building POM (may not be this project's POM).

Project ID: null:drools-api:jar:null

Reason: Cannot find parent: org.drools:drools for project: null:drools-api:jar:null for project null:drools-api:jar:null