made class more forgiving on ASN.1 encodings

Author: dghgit

core/src/main/java/org/bouncycastle/asn1/x509/Extensions.java

@@ -71,10 +71,8 @@ else if (obj != null)
     private Extensions(
         ASN1Sequence seq)
     {
-        if (seq.size() == 0)
-        {
-            throw new IllegalArgumentException("empty extension sequence found");
-        }
+        // it's tempting to check there's at least one entry in the sequence. Don't!
+        // It turns out there's quite a few empty extension blocks out there...
 
         Enumeration e = seq.getObjects();