DeviceCredentialsCacheTest total DB calls reduced from 2 to 3 due to nulls cached at findDeviceCredentialsByCredentialsId

dao/src/test/java/org/thingsboard/server/dao/service/DeviceCredentialsCacheTest.java

@@ -127,10 +127,10 @@ public class DeviceCredentialsCacheTest extends AbstractServiceTest {
 
         when(deviceCredentialsDao.findByCredentialsId(SYSTEM_TENANT_ID, CREDENTIALS_ID_1)).thenReturn(null);
 
-        deviceCredentialsService.findDeviceCredentialsByCredentialsId(CREDENTIALS_ID_1);
-        deviceCredentialsService.findDeviceCredentialsByCredentialsId(CREDENTIALS_ID_1);
+        deviceCredentialsService.findDeviceCredentialsByCredentialsId(CREDENTIALS_ID_1); // cache miss, DB read (not found), Cache put null value
+        deviceCredentialsService.findDeviceCredentialsByCredentialsId(CREDENTIALS_ID_1); // cache hit (null value, credentials not found)
 
-        verify(deviceCredentialsDao, times(3)).findByCredentialsId(SYSTEM_TENANT_ID, CREDENTIALS_ID_1);
+        verify(deviceCredentialsDao, times(2)).findByCredentialsId(SYSTEM_TENANT_ID, CREDENTIALS_ID_1);
     }
 
     private DeviceCredentialsService unwrapDeviceCredentialsService() throws Exception {