diff --git a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/ProfileDiscoveryCallback.kt b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/ProfileDiscoveryCallback.kt
index b70e0d8..d51eb74 100644
--- a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/ProfileDiscoveryCallback.kt
+++ b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/ProfileDiscoveryCallback.kt
@@ -1,5 +1,5 @@
 package net.typeblog.lpac_jni
 
 interface ProfileDiscoveryCallback {
-    fun onDiscovered(servers: List<String>)
+    fun onDiscovered(servers: Set<String>)
 }
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c b/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c
index be490fd..3f2dff1 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c
@@ -1,7 +1,7 @@
 #include <string.h>
 #include <malloc.h>
 #include "interface-wrapper.h"
-#include "utils.h"
+#include "lpac-convertor.h"
 
 static jmethodID method_apdu_connect;
 static jmethodID method_apdu_disconnect;
@@ -95,7 +95,15 @@ http_interface_transmit(struct euicc_ctx *ctx, const char *url, uint32_t *rcode,
     jbyteArray txArr = (*env)->NewByteArray(env, (jsize) tx_len);
     (*env)->SetByteArrayRegion(env, txArr, 0, (jsize) tx_len, (const jbyte *) tx);
 
-    jobject header_list = to_string_list(env, (char **) headers);
+    jobject header_list = new_array_list(env);
+    jclass header_list_class = (*env)->GetObjectClass(env, header_list);
+    jmethodID add_header = (*env)->GetMethodID(env, header_list_class, "add", "(Ljava/lang/Object;)Z");
+
+    for (int i = 0; headers[i] != NULL; i++) {
+        jstring header = toJString(env, headers[i]);
+        (*env)->CallBooleanMethod(env, header_list, add_header, header);
+        (*env)->DeleteLocalRef(env, header);
+    }
 
     jobject ret = (*env)->CallObjectMethod(env, LPAC_JNI_CTX(ctx)->http_interface,
                                            method_http_transmit, jurl, txArr, header_list);
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/utils.c b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c
similarity index 92%
rename from libs/lpac-jni/src/main/jni/lpac-jni/utils.c
rename to libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c
index 542ccc4..da714ac 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/utils.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c
@@ -1,4 +1,4 @@
-#include "utils.h"
+#include "lpac-convertor.h"
 #include <malloc.h>
 #include <string.h>
 #include <syslog.h>
@@ -145,19 +145,6 @@ jobject to_string_set(JNIEnv *env, char **values) {
     return elements;
 }
 
-jobject to_string_list(JNIEnv *env, char **values) {
-    jclass set_class = (*env)->FindClass(env, ARRAY_LIST_CLASS);
-    jmethodID set_constructor = (*env)->GetMethodID(env, set_class, "<init>", "()V");
-    jobject elements = (*env)->NewObject(env, set_class, set_constructor);
-    jmethodID add_element = (*env)->GetMethodID(env, set_class, "add", "(Ljava/lang/Object;)Z");
-    jstring element = NULL;
-    for (jsize index = 0; values[index] != NULL; index++) {
-        element = toJString(env, values[index]);
-        (*env)->CallBooleanMethod(env, elements, add_element, element);
-    }
-    return elements;
-}
-
 jobject build_profile_metadata(JNIEnv *env, struct es8p_metadata *metadata) {
     if (metadata == NULL) return NULL;
 
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/utils.h b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h
similarity index 96%
rename from libs/lpac-jni/src/main/jni/lpac-jni/utils.h
rename to libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h
index 617f5f4..cc7c568 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/utils.h
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h
@@ -31,8 +31,6 @@ jobject to_version(JNIEnv *env, const char *version);
 
 jobject to_string_set(JNIEnv *env, char **values);
 
-jobject to_string_list(JNIEnv *env, char **values);
-
 jobject build_profile_metadata(JNIEnv *env, struct es8p_metadata *metadata);
 
 jobject to_profile_management_operation(enum es10b_profile_management_operation operation);
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-discovery.c b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-discovery.c
index e2246fc..446521b 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-discovery.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-discovery.c
@@ -4,7 +4,7 @@
 #include <string.h>
 #include <malloc.h>
 #include <syslog.h>
-#include "utils.h"
+#include "lpac-convertor.h"
 #include "lpac-discovery.h"
 
 JNIEXPORT jobject JNICALL
@@ -52,7 +52,7 @@ Java_net_typeblog_lpac_1jni_LpacJni_discoveryProfile(
 
     jclass callback_class = (*env)->GetObjectClass(env, callback);
     jmethodID on_discovered = (*env)->GetMethodID(env, callback_class, "onDiscovered",
-                                                  "(Ljava/util/List;)V");
+                                                  "(Ljava/util/Set;)V");
 
     const char *_address = (*env)->GetStringUTFChars(env, address, NULL);
     const char *_imei = NULL;
@@ -95,7 +95,7 @@ Java_net_typeblog_lpac_1jni_LpacJni_discoveryProfile(
         goto out;
     }
 
-    (*env)->CallVoidMethod(env, callback, on_discovered, to_string_list(env, smdp_list));
+    (*env)->CallVoidMethod(env, callback, on_discovered, to_string_set(env, smdp_list));
 
     out:
 
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-download.c b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-download.c
index b1ab73e..e069383 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-download.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-download.c
@@ -3,7 +3,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
-#include "utils.h"
+#include "lpac-convertor.h"
 #include "lpac-download.h"
 
 static jobject download_state_preparing;
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-jni.c b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-jni.c
index 9196ff7..0b6b496 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-jni.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-jni.c
@@ -9,7 +9,7 @@
 #include "lpac-download.h"
 #include "lpac-notifications.h"
 #include "lpac-discovery.h"
-#include "utils.h"
+#include "lpac-convertor.h"
 #include "interface-wrapper.h"
 
 JavaVM *jvm = NULL;
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-notifications.c b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-notifications.c
index a581d40..e6c0069 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-notifications.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-notifications.c
@@ -2,7 +2,7 @@
 #include <euicc/es10b.h>
 #include <malloc.h>
 #include <syslog.h>
-#include "utils.h"
+#include "lpac-convertor.h"
 #include "lpac-notifications.h"
 
 JNIEXPORT jobject JNICALL