ContraintTransformation: Ignore non-task period contraints

Signed-off-by: Alexander Diewald <diewald@fortiss.org>

org.fortiss.af3.exploration.alg/src/org/fortiss/af3/exploration/alg/dse/.ratings

-Explorer.java c7cc31f9a4680e3faae757ef2fc752ee2dfdcdf6 YELLOW
-ImplicitExplorationTargetFactory.java e2f0370fd2a3e82bf770d87f0f2fdacd5f866532 RED
-InputProviderGenerator.java 92a0fc0936a462ede72f14223b64a5ca340dab80 YELLOW
-InternalSpecificationProvider.java c15e6ebf95fc2d0779a42ebf73aa5160bc9611e4 YELLOW
-RandomExploration.java 3358df8f6cc82a336d3b6283e92f92acb7190088 RED
-SuperSetProviderGenerator.java 06391faf265f36298c2e5ed52504746ae312738b YELLOW
+Explorer.java c7cc31f9a4680e3faae757ef2fc752ee2dfdcdf6 YELLOW
+ImplicitExplorationTargetFactory.java 9299f1fe962dd8b38c099bffcaafff52d030b41a RED
+InputProviderGenerator.java 92a0fc0936a462ede72f14223b64a5ca340dab80 YELLOW
+InternalSpecificationProvider.java c15e6ebf95fc2d0779a42ebf73aa5160bc9611e4 YELLOW
+RandomExploration.java 3358df8f6cc82a336d3b6283e92f92acb7190088 RED
+SuperSetProviderGenerator.java 06391faf265f36298c2e5ed52504746ae312738b YELLOW

org.fortiss.af3.exploration.alg/src/org/fortiss/af3/exploration/alg/dse/ImplicitExplorationTargetFactory.java

@@ -134,9 +134,7 @@ public class ImplicitExplorationTargetFactory {
 				PeriodicConstraint.class)) {
 			IModelElement taskME = pC.getEvent().getEntity();
 			if(!(taskME instanceof Task)) {
-				throw new ConstraintGenerationException(PeriodConstraint.class,
-						"One of the periodic constraints is invalid." +
-								" It does not point to a Task. ID: " + pC.getId() + ".");
+				continue;
 			}
 			ITaskAdapter task = taskMapper.getAdapter((Task)taskME);