Fixed crash

app/src/main/java/eu/faircode/email/Helper.java

@@ -1564,17 +1564,6 @@ public class Helper {
         return result;
     }
 
-    @SuppressWarnings("unchecked")
-    public static <T> T[] concat(T[] a, T[] b) {
-        if (a == null)
-            a = (T[]) new Object[0];
-        if (b == null)
-            b = (T[]) new Object[0];
-        T[] both = Arrays.copyOf(a, a.length + b.length);
-        System.arraycopy(b, 0, both, a.length, b.length);
-        return both;
-    }
-
     static boolean equal(String[] a1, String[] a2) {
         if (a1 == null && a2 == null)
             return true;