For an undefined relationship in an entity class, the following hint appears: 'The entity relation is not defined'.
'relationship' should be used instead of 'relation'.
Issue '133015' Integrated in NB_Trunk_Production #145 : http://hg.netbeans.org/main/rev/f542ee619d85,
with comment: #133015: 'relation' used instead of 'relationship'
The fix has been ported into the release61_fixes branch.