Bug in domain classes dependencies diagram for Grails domain model

Using IDEA 8.1.1, I noted a bug in domain classes dependencies diagram for Grails domain model representation a one-to-one mapping relationship between two entities.

Following 1-to-1 relationships are represented as 1-to-many in domain classes dependencies diagram,

Case 1:

class Face {
    Nose nose
}
class Nose {
}

Case 2:

class Face {
    Nose nose
}
class Nose {
    static belongsTo = [face:Face]
}

In addition, there are no distinction in arrow for representing bidirectional and uni-directional relationships. All relationships are linked by a one-sided arrow.

Please comment. Thank you.