build: Downgrade to Java 1.7

Downgrading is necessary to keep compatibility with Android

Change-Id: I9269d3ec32fd87bdd487ec91fab0f6fa87c7de23
diff --git a/src/test/java/com/intel/jndn/utils/TestHelper.java b/src/test/java/com/intel/jndn/utils/TestHelper.java
index a73aba4..fbf931e 100644
--- a/src/test/java/com/intel/jndn/utils/TestHelper.java
+++ b/src/test/java/com/intel/jndn/utils/TestHelper.java
@@ -24,8 +24,6 @@
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import java.util.stream.Collectors;
-import java.util.stream.IntStream;
 import net.named_data.jndn.Data;
 import net.named_data.jndn.Face;
 import net.named_data.jndn.Name;
@@ -51,15 +49,19 @@
   }
 
   public static List<CompletableFuture<Data>> buildFutureSegments(Name name, int from, int to) {
-    return buildSegments(name, from, to).stream()
-            .map((d) -> CompletableFuture.completedFuture(d))
-            .collect(Collectors.toList());
+    List<CompletableFuture<Data>> list = new ArrayList<>();
+    for (Data d : buildSegments(name, from, to)) {
+      list.add(CompletableFuture.completedFuture(d));
+    }
+    return list;
   }
 
   public static List<Data> buildSegments(Name name, int from, int to) {
-    return IntStream.range(from, to).boxed()
-            .map((i) -> buildData(new Name(name).appendSegment(i), i.toString(), to - 1))
-            .collect(Collectors.toList());
+    List<Data> list = new ArrayList<>();
+    for (Integer i = from; i < to; i++) {
+      list.add(buildData(new Name(name).appendSegment(i), i.toString(), to - 1));
+    }
+    return list;
   }
 
   public static Data buildData(Name name, String content) {