DEF-2639 Classes.dex is now always built again (bugfix) (#40)

* DEF-2639 Classes.dex is now always built again (bugfix)

* DEF-2639 review fixes

server/src/main/java/com/defold/extender/Extender.java

@@ -391,10 +391,6 @@ public File buildClassesDex() throws ExtenderException {
             extJars.addAll(getJars(extDir));
         }
 
-        if (extJars.isEmpty()) {
-            return null;
-        }
-
         Map<String, Object> context = context(platformConfig.context);
         context.put("classes_dex", classesDex.getAbsolutePath());
         context.put("jars", extJars);

server/src/test/java/com/defold/extender/IntegrationTest.java

@@ -320,8 +320,13 @@ public void buildAndroidCheckClassesDex() throws IOException, ExtenderClientExce
 
         // Verify that classes.dex contains our Dummy class
         DexFile dexFile = DexFileFactory.loadDexFile(tmpClassesDexPath.toFile().getAbsolutePath(), 19 ); // api level
+
+        List<String> expected = new ArrayList<>();
+        expected.add("Lcom/svenandersson/dummy/Dummy;");
+        expected.add("Lcom/defoldtest/engine/Engine;");
+
         for (ClassDef classDef: dexFile.getClasses()) {
-            assertEquals("Lcom/svenandersson/dummy/Dummy;", classDef.getType());
+            assertTrue( expected.contains( classDef.getType() ) );
         }
     }
 }

server/test-data/sdk/a/defoldsdk/extender/build.yml

@@ -60,7 +60,7 @@ platforms:
 
   armv7-android:
     context:
-        engineJars: []
+        engineJars: ["{{dynamo_home}}/share/java/Engine.jar"]
         engineLibs: []
 
     exePrefix: 'lib'

server/test-data/sdk/a/defoldsdk/share/java/build.sh

@@ -0,0 +1,3 @@
+
+javac  -source 1.6 -target 1.6  -cp . com/defoldtest/engine/Engine.java
+jar cvf Engine.jar com

server/test-data/sdk/a/defoldsdk/share/java/com/defoldtest/engine/Engine.java

@@ -0,0 +1,7 @@
+package com.defoldtest.engine;
+
+public class Engine {
+    static public String Test() {
+        return "Hello from the SDK!!!";
+    }
+}