Duplications handling

There is a case when groups filter or entries filter returns more than one value. This is an error from plugin point of view because plugin should not decide which group or entry to use. Too many risks in security domain.

There are 2 ways how to solve the issue:

• improve group or entry filter, make it less general, so it should return only one value
• for some testing reasons, developer can disable error and convert it to warning. It's possible with configuration property Ignore Duplicates. In this case, the first value from the filter result is selected and Maven reports its UUID as a warning.