Add first idea for a metric implementation for dmn verifications

dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/verification/DmnVerificationMetricsService.java

+package de.unikoblenz.fgbks.core.dmn.verification;
+
+import de.unikoblenz.fgbks.core.dmn.verification.metrics.Metric;
+import de.unikoblenz.fgbks.core.dmn.verification.verifier.types.VerificationType;
+import java.util.HashMap;
+import javax.enterprise.context.ApplicationScoped;
+
+@ApplicationScoped
+public class DmnVerificationMetricsService {
+
+  private HashMap<VerificationType, Metric> metrics;
+
+}

dmnverifierapi/src/main/java/de/unikoblenz/fgbks/core/dmn/verification/metrics/Metric.java

+package de.unikoblenz.fgbks.core.dmn.verification.metrics;
+
+import de.unikoblenz.fgbks.core.dmn.verification.verifier.types.VerificationType;
+import java.util.ArrayList;
+import java.util.List;
+
+public class Metric {
+
+  VerificationType type;
+  private List<Integer> executionTimes;
+
+  public Metric() {
+    this.executionTimes = new ArrayList<>();
+  }
+
+  public int getAmountOfExecutions() {
+    return executionTimes.size();
+  }
+
+  public double getAverageExecutionTime() {
+    return executionTimes.stream().mapToInt(Integer::intValue).average().orElseGet(() -> 0);
+  }
+
+  public int getTotalExecutionTime() {
+    return executionTimes.stream().mapToInt(Integer::intValue).sum();
+  }
+
+  @Override
+  public String toString() {
+    return super.toString();
+  }
+}