decrypt seems to work. At least in one special corner case :-) I'll commit, so Edouard can take a look.

android/pEpJNIAdapter.iml

@@ -70,9 +70,7 @@
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/dependency-cache" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/incremental" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/lint" />
-      <excludeFolder url="file://$MODULE_DIR$/build/intermediates/lint-cache" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/manifests" />
-      <excludeFolder url="file://$MODULE_DIR$/build/intermediates/mockable-android-21.jar" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/res" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/resources" />
       <excludeFolder url="file://$MODULE_DIR$/build/intermediates/rs" />
@@ -81,8 +79,6 @@
       <excludeFolder url="file://$MODULE_DIR$/build/openssl-android-1" />
       <excludeFolder url="file://$MODULE_DIR$/build/outputs" />
       <excludeFolder url="file://$MODULE_DIR$/build/pEpEngine-android-1" />
-      <excludeFolder url="file://$MODULE_DIR$/build/reports" />
-      <excludeFolder url="file://$MODULE_DIR$/build/test-results" />
       <excludeFolder url="file://$MODULE_DIR$/build/tmp" />
     </content>
     <content url="file://$MODULE_DIR$/../src">

src/org/pEp/jniadapter/Blob.java

@@ -5,7 +5,7 @@ public class Blob {
     public String mime_type;
     public String filename;
 
-    Blob() {
+    public Blob() {
         mime_type = "application/octet-stream";
     }