Not allow null value for all control metrics, revise unit test

Current implementation allows null value from REST API.
Null metric value leads the metrics database to not store the value
properly. This commit tries to fix this issue.

Change-Id: I82a5fd0d11671db4d2136a3fc40090b7684ba91a

@@ -57,6 +57,15 @@ public class ControlMetricsCollectorResourceTest extends JerseyTest {
     private static final String PREFIX = "collector";
 
     /**
+     * Constructs a control metrics collector resource test instance.
+     */
+    public ControlMetricsCollectorResourceTest() {
+        super(new WebAppDescriptor.Builder("javax.ws.rs.Application",
+                CPManWebApplication.class.getCanonicalName())
+                .servletClass(ServletContainer.class).build());
+    }
+
+    /**
      * Sets up the global values for all the tests.
      */
     @Before
@@ -67,6 +76,9 @@ public class ControlMetricsCollectorResourceTest extends JerseyTest {
         BaseResource.setServiceDirectory(testDirectory);
     }
 
+    /**
+     * Tests CPU metrics POST through REST API.
+     */
     @Test
     public void testCpuMetricsPost() {
         mockControlPlaneMonitorService.updateMetric(anyObject(), anyInt(),
@@ -76,6 +88,9 @@ public class ControlMetricsCollectorResourceTest extends JerseyTest {
         basePostTest("cpu-metrics-post.json", PREFIX + "/cpu_metrics");
     }
 
+    /**
+     * Tests memory metrics POST through REST API.
+     */
     @Test
     public void testMemoryMetricsPost() {
         mockControlPlaneMonitorService.updateMetric(anyObject(), anyInt(),
@@ -85,16 +100,22 @@ public class ControlMetricsCollectorResourceTest extends JerseyTest {
         basePostTest("memory-metrics-post.json", PREFIX + "/memory_metrics");
     }
 
+    /**
+     * Tests disk metrics POST through REST API.
+     */
     @Test
-    public void testDiskMetricsWithNullName() {
+    public void testDiskMetrics() {
         mockControlPlaneMonitorService.updateMetric(anyObject(), anyInt(), anyString());
         expectLastCall().times(4);
         replay(mockControlPlaneMonitorService);
         basePostTest("disk-metrics-post.json", PREFIX + "/disk_metrics");
     }
 
+    /**
+     * Tests network metrics POST through REST API.
+     */
     @Test
-    public void testNetworkMetricsWithNullName() {
+    public void testNetworkMetrics() {
         mockControlPlaneMonitorService.updateMetric(anyObject(), anyInt(), anyString());
         expectLastCall().times(8);
         replay(mockControlPlaneMonitorService);
@@ -123,12 +144,6 @@ public class ControlMetricsCollectorResourceTest extends JerseyTest {
         assertThat(response.getStatus(), is(HttpURLConnection.HTTP_OK));
     }
 
-    public ControlMetricsCollectorResourceTest() {
-        super(new WebAppDescriptor.Builder("javax.ws.rs.Application",
-                CPManWebApplication.class.getCanonicalName())
-                .servletClass(ServletContainer.class).build());
-    }
-
     /**
      * Assigns an available port for the test.
      *