Fix WarningsAnnotationsAggregator not aggregating

I've always been a bit confused at the aggregate warning report when doing a Jenkins build. It seemed like it only counted one run of the matrix. I finally snapped and went and looked at the code.

The section which actually adds the result to the aggregate is guarded by a containsKey on the results map. In other words it only allows adding one result per parser type.

This is fixed here. Thanks.