Fix checkstyle issues

src/main/java/be/cylab/java/wowa/training/Factory.java

 package be.cylab.java.wowa.training;
 
-import java.lang.reflect.InvocationTargetException;
 
 /**
  * Class to generate objects.
@@ -18,13 +17,14 @@ public class Factory {
     /**
      * @return
      */
-    public AbstractSolution createSolutionObject(final int a) {
+    public final AbstractSolution createSolutionObject(final int a) {
         if (this.solution_type instanceof SolutionDistance) {
             return new SolutionDistance(a);
         } else if (this.solution_type instanceof SolutionAUC) {
             return new SolutionAUC(a);
         } else {
-            throw new IllegalArgumentException("Provide o correct type of Solution");
+            throw new IllegalArgumentException(
+                    "Provide o correct type of Solution");
         }
     }
 }

src/main/java/be/cylab/java/wowa/training/Trainer.java

@@ -95,7 +95,8 @@ public class Trainer {
 
         List<AbstractSolution> population = new ArrayList<>();
         for (int i = 0; i < population_size; i++) {
-            AbstractSolution solution = this.factory.createSolutionObject(number_of_weights);
+            AbstractSolution solution
+                    = this.factory.createSolutionObject(number_of_weights);
             population.add(solution);
         }
         return population;