Fix jvpp coverity issues #2

- synchronize AbstractFutureJvppInvoker.getRequests
- handle registry & jvpp close in API usage examples

Change-Id: I918bf864b8212fde04f0d9194037f1c6a810fc3f
Signed-off-by: Marek Gradzki <mgradzki@cisco.com>

vpp-api/java/jvpp-registry/io/fd/vpp/jvpp/future/AbstractFutureJVppInvoker.java

@@ -51,7 +51,7 @@ public abstract class AbstractFutureJVppInvoker implements FutureJVppInvoker {
         this.requests = Objects.requireNonNull(requestMap, "Null requestMap");
     }
 
-    protected final Map<Integer, CompletableFuture<? extends JVppReply<?>>> getRequests() {
+    protected synchronized final Map<Integer, CompletableFuture<? extends JVppReply<?>>> getRequests() {
         return this.requests;
     }
 

vpp-api/java/jvpp-registry/io/fd/vpp/jvpp/test/ConnectionTest.java

@@ -27,14 +27,15 @@ public class ConnectionTest {
 
     private static void testConnect() throws Exception {
         System.out.println("Testing JNI connection with JVppRegistry");
-        JVppRegistry registry = new JVppRegistryImpl("ConnectionTest");
-        System.out.println("Successfully connected to vpp");
-
-        Thread.sleep(5000);
-
-        System.out.println("Disconnecting...");
-        registry.close();
-        Thread.sleep(1000);
+        final JVppRegistry registry = new JVppRegistryImpl("ConnectionTest");
+        try {
+            System.out.println("Successfully connected to vpp");
+            Thread.sleep(5000);
+            System.out.println("Disconnecting...");
+            Thread.sleep(1000);
+        } finally {
+            registry.close();
+        }
     }
 
     public static void main(String[] args) throws Exception {