fixed test cases

dependency-check-core/src/main/java/org/owasp/dependencycheck/data/nvdcve/CveDB.java

@@ -230,6 +230,16 @@ public final class CveDB implements AutoCloseable {
         }
     }
 
+    /**
+     * Method added for testing, returns the current usage count of the CveDB
+     * singleton.
+     *
+     * @return the current usage of the CveDB singleton
+     */
+    protected synchronized int getUsageCount() {
+        return usageCount;
+    }
+
     /**
      * Opens the database connection. If the database does not exist, it will
      * create a new one.