Handle empty strings in component annotations

When a string such as "permission," is used with @UsesPermission, it
results in an empty string appearing in the permission list, and in
the <uses-permission> annotation in AndroidManifest.xml. Google Play
Store will reject such apps. This commit filters out empty strings
during component processing and during compilation to fix this issue.

Fixes #1108

Change-Id: Icafe2fa658f83f046dacfec98d3f0cb8f8b90755

appinventor/buildserver/src/com/google/appinventor/buildserver/Compiler.java

@@ -1748,7 +1748,9 @@ private void loadJsonInfo(ConcurrentMap<String, Set<String>> infoMap, String tar
         Set<String> infoSet = Sets.newHashSet();
         for (int j = 0; j < infoArray.length(); ++j) {
           String info = infoArray.getString(j);
-          infoSet.add(info);
+          if (!info.isEmpty()) {
+            infoSet.add(info);
+          }
         }
 
         if (!infoSet.isEmpty()) {

appinventor/components/src/com/google/appinventor/components/scripts/ComponentProcessor.java

@@ -909,34 +909,34 @@ private void processComponent(Element element) {
     UsesPermissions usesPermissions = element.getAnnotation(UsesPermissions.class);
     if (usesPermissions != null) {
       for (String permission : usesPermissions.permissionNames().split(",")) {
-        componentInfo.permissions.add(permission.trim());
+        updateWithNonEmptyValue(componentInfo.permissions, permission);
       }
     }
 
     // Gather library names.
     UsesLibraries usesLibraries = element.getAnnotation(UsesLibraries.class);
     if (usesLibraries != null) {
       for (String library : usesLibraries.libraries().split(",")) {
-        componentInfo.libraries.add(library.trim());
+        updateWithNonEmptyValue(componentInfo.libraries, library);
       }
     }
 
     // Gather native library names.
     UsesNativeLibraries usesNativeLibraries = element.getAnnotation(UsesNativeLibraries.class);
     if (usesNativeLibraries != null) {
       for (String nativeLibrary : usesNativeLibraries.libraries().split(",")) {
-        componentInfo.nativeLibraries.add(nativeLibrary.trim());
+        updateWithNonEmptyValue(componentInfo.nativeLibraries, nativeLibrary);
       }
       for (String v7aLibrary : usesNativeLibraries.v7aLibraries().split(",")) {
-        componentInfo.nativeLibraries.add(v7aLibrary.trim() + ARMEABI_V7A_SUFFIX);
+        updateWithNonEmptyValue(componentInfo.nativeLibraries, v7aLibrary.trim() + ARMEABI_V7A_SUFFIX);
       }
     }
 
     // Gather required files.
     UsesAssets usesAssets = element.getAnnotation(UsesAssets.class);
     if (usesAssets != null) {
       for (String file : usesAssets.fileNames().split(",")) {
-        componentInfo.assets.add(file.trim());
+        updateWithNonEmptyValue(componentInfo.assets, file);
       }
     }
 
@@ -945,7 +945,7 @@ private void processComponent(Element element) {
     if (usesActivities != null) {
       try {
         for (ActivityElement ae : usesActivities.activities()) {
-          componentInfo.activities.add(activityElementToString(ae));
+          updateWithNonEmptyValue(componentInfo.activities, activityElementToString(ae));
         }
       } catch (IllegalAccessException e) {
         messager.printMessage(Diagnostic.Kind.ERROR, "IllegalAccessException when gathering " +
@@ -963,7 +963,7 @@ private void processComponent(Element element) {
     if (usesBroadcastReceivers != null) {
       try {
         for (ReceiverElement re : usesBroadcastReceivers.receivers()) {
-          componentInfo.broadcastReceivers.add(receiverElementToString(re));
+          updateWithNonEmptyValue(componentInfo.broadcastReceivers, receiverElementToString(re));
         }
       } catch (IllegalAccessException e) {
         messager.printMessage(Diagnostic.Kind.ERROR, "IllegalAccessException when gathering " +
@@ -1554,4 +1554,11 @@ public Boolean visitDeclared(DeclaredType t, Set<String> types) {
       }, visitedTypes);
     }
   }
+
+  private void updateWithNonEmptyValue(Set<String> collection, String value) {
+    String trimmedValue = value.trim();
+    if (!trimmedValue.isEmpty()) {
+      collection.add(trimmedValue);
+    }
+  }
 }