Refactor: move method to get annotated double value

- Move to AnnotationKeys to remove code duplication

Change-Id: Icf8b4322fc88e43ab531402d0e403a38d186f48e

@@ -28,4 +28,23 @@ public final class AnnotationKeys {
      * Annotation key for latency.
      */
     public static final String LATENCY = "latency";
+
+    /**
+     * Returns the value annotated object for the specified annotation key.
+     * The annotated value is expected to be String that can be parsed as double.
+     * If parsing fails, the returned value will be 1.0.
+     *
+     * @param annotated annotated object whose annotated value is obtained
+     * @param key key of annotation
+     * @return double value of annotated object for the specified key
+     */
+    public static double getAnnotatedValue(Annotated annotated, String key) {
+        double value;
+        try {
+            value = Double.parseDouble(annotated.annotations().value(key));
+        } catch (NumberFormatException e) {
+            value = 1.0;
+        }
+        return value;
+    }
 }

@@ -21,6 +21,8 @@ import org.onlab.onos.net.resource.LinkResourceService;
 
 import java.util.Objects;
 
+import static org.onlab.onos.net.AnnotationKeys.getAnnotatedValue;
+
 /**
  * Constraint that evaluates an arbitrary link annotated value is under the specified threshold.
  */
@@ -65,25 +67,6 @@ public class AnnotationConstraint extends BooleanConstraint {
         return value <= threshold;
     }
 
-    /**
-     * Returns the annotated value of the specified link. The annotated value
-     * is expected to be String that can be parsed as double. If parsing fails,
-     * the returned value will be 1.0.
-     *
-     * @param link link whose annotated value is obtained
-     * @param key key of link annotation
-     * @return double value of link annotation for the specified key
-     */
-    private double getAnnotatedValue(Link link, String key) {
-        double value;
-        try {
-            value = Double.parseDouble(link.annotations().value(key));
-        } catch (NumberFormatException e) {
-            value = 1.0;
-        }
-        return value;
-    }
-
     @Override
     public double cost(Link link, LinkResourceService resourceService) {
         if (isValid(link, resourceService)) {

@@ -26,6 +26,7 @@ import java.time.temporal.ChronoUnit;
 import java.util.Objects;
 
 import static org.onlab.onos.net.AnnotationKeys.LATENCY;
+import static org.onlab.onos.net.AnnotationKeys.getAnnotatedValue;
 
 /**
  * Constraint that evaluates the latency through a path.
@@ -48,16 +49,7 @@ public class LatencyConstraint implements Constraint {
 
     @Override
     public double cost(Link link, LinkResourceService resourceService) {
-        String value = link.annotations().value(LATENCY);
-
-        double latencyInMicroSec;
-        try {
-            latencyInMicroSec = Double.parseDouble(value);
-        } catch (NumberFormatException e) {
-            latencyInMicroSec = 1.0;
-        }
-
-        return latencyInMicroSec;
+        return getAnnotatedValue(link, LATENCY);
     }
 
     @Override