Port #402 to 3.1.x

Author: tjcelaya

java-manta-client/src/main/java/com/joyent/manta/client/MantaClient.java

@@ -700,6 +700,7 @@ public Stream<MantaObject> listObjects(final String path) throws IOException {
          */
         try {
             if (!itr.hasNext()) {
+                itr.close();
                 return Stream.empty();
             }
         } catch (UncheckedIOException e) {

java-manta-client/src/test/java/com/joyent/manta/client/MantaClientTest.java

@@ -0,0 +1,58 @@
+package com.joyent.manta.client;
+
+import com.joyent.manta.config.TestConfigContext;
+import org.mockito.Mockito;
+import org.testng.annotations.AfterTest;
+import org.testng.annotations.Test;
+
+import java.io.IOException;
+import java.util.stream.Stream;
+
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class MantaClientTest {
+
+    @AfterTest
+    public void teardown() {
+        Mockito.validateMockitoUsage();
+    }
+
+    @Test
+    public void listObjectsDoesNotLeakConnectionsWhenThereAreResults() throws IOException {
+        // BasicHttpClientConnectionManager maintains a single connection
+
+        final MantaDirectoryListingIterator iteratorMock = mock(MantaDirectoryListingIterator.class);
+        when(iteratorMock.hasNext()).thenReturn(true);
+
+        final MantaClient client = new MantaClient(new TestConfigContext());
+        final MantaClient clientSpy = spy(client);
+        doReturn(iteratorMock).when(clientSpy).streamingIterator(anyString());
+
+        final Stream<MantaObject> listing = clientSpy.listObjects("/");
+        listing.close();
+
+        verify(iteratorMock).close();
+    }
+
+    @Test
+    public void listObjectsDoesNotLeakConnectionsWhenNoResults() throws IOException {
+        // BasicHttpClientConnectionManager maintains a single connection
+
+        final MantaDirectoryListingIterator iteratorMock = mock(MantaDirectoryListingIterator.class);
+        when(iteratorMock.hasNext()).thenReturn(false);
+
+        final MantaClient client = new MantaClient(new TestConfigContext());
+        final MantaClient clientSpy = spy(client);
+        doReturn(iteratorMock).when(clientSpy).streamingIterator(anyString());
+
+        final Stream<MantaObject> listing = clientSpy.listObjects("/");
+        listing.close();
+
+        verify(iteratorMock).close();
+    }
+}