method used to compare two objects.
this method is used in Collection to order items, and MUST be
consistent with the equals method (eache method should return 0/true in the same cases).
Parameters: o - object to compare See Also:java.lang.Comparable.compareTo(java.lang.Object) 0 if both objects are equals,<0 if 0 is lesser than the RolePrincipal,>0 if 0 is greater than the RolePrincipal See Also:java.lang.Comparable.compareTo(java.lang.Object)
compare an object to this RolePrincipal.
override the Object's equals method.
Parameters: another - object to compare true if another is equals to this RolePrincipal